Training Excellence in Credit, AR & O2C. Callisto Grand values every role equally.

The Callisto Grand philosophy

The Callisto Grand philosophy is dedicated to every aspect of Credit Management and Order to Cash across a wide geography.
Trade Receivables is almost every company’s largest, most complex Current Asset and business-critical component of Working Capital and Cash Flow.

All roles in C2C, I2C, O2C, AR, Accounts Receivable, Risk, Collections, Cash Application, Disputes, Billing, Database and Reporting are the guardians of this asset, responsible for protecting the profit margin and impacting business growth.

Callisto Grand welcomes everyone and has development programmes whether you are an Associate, Specialist, Subject Matter Expert (SME), Team Leader, Credit Controller, Manager, Global Process Owner (GPO) or Director in any type of business, Shared Service Centre (SSC), Global Business Services (GBS) or Business Process Outsourcing (BPO).

Irrespective of job title or experience, your role is essential and Callisto Grand promotes Credit / O2C as a respected, dynamic, challenging, varied, exciting and rewarding profession.

Our team and advisory network comprise highly knowledgeable and dedicated professionals with a wealth of global experience.
The Callisto Grand Academy training, qualifications, analytics, coaching, and consultancy are all designed and developed to meet the changing complexities in today’s business environment, supporting all generations from newcomers to directors.

From Our Founder & CEO

My professional odyssey began unexpectedly, stepping in as a Credit Controller. That moment ignited my passion for a career that spans over four decades in the ever-evolving landscape of Credit / O2C and across various work environments like Centralized, Decentralized and Global Business Services.

Callisto Grand, the name inspired by my grandfather’s houseboat, is more than an organization; it’s a celebration of the enduring enchantment found in the world of Credit. Few roles offer the unique ability to impact every stakeholder in a business positively. We believe work should transcend the confines of a 9 to 5 process or routine. Callisto Grand is committed to sharing the magic that makes each day more than just a process.

The greatest reward for my team and me is connecting with those who ‘get it’—individuals who share our passion.
We’re excited to meet you at our roundtables, conferences and training programmes sharing how you too can experience the same sense of fulfilment.
Looking forward to connecting,

Mark Harrison
Founder and CEO, Callisto Grand


The average annual attrition rate in the SSC and GBS sector is 15-20%. Usually the person leaving will not work a lot, the person in the trial period will not contribute much and the ones training the newjoiners will have a lower operational capacity.

It is a huge loss of time, money, talent and opportunity that directly affects your Order to Cash as a whole and your profit margins.

The main way to overcome this challenge is by investing in your Talent. Engaged employees with a dynamic and fun career and an idea how they can develop will not leave you that easily, especially if they are supported in career development efforts.

That’s where We come in. You can leave this matter to us: your O2C and Credit efficiency and effectiveness will become better and you will retain highly skilled and motivated employees. Win-win-win!


Double digit overdues are a long way from a Culture of Excellence. If your numbers exceed 2.5% in any or all of: overdue %, unapplied cash, credit notes vs sales or attrition rates…

It confirms a weakness in one or more internal policy, process or procedure. There’s a lot to improve, and we’ve got a game-changing strategy. We’re using technology, industry knowledge, and a network of virtual and local experts to quickly solve each manager’s problem — from a high past due %, attrition rates or pressure to improve effciency and/or reduce costs.

At all levels, including Senior Management , the root cause is identified as „They don’t know what they don’t know”. And they will not learn it unless it is taught and showed to them.  Something that we can do as your guides to optimal Working Capital and AR turned Cash.

Critical KPI objectives and career progression to senior management can only be achieved by embracing Culture, Leadership, Talent Development, Technology, Policies, Procedures, Employer Branding and Diversity simultaneously.


The most applicable, interactive and relavant, success guaranteed solutions you’ll find led by passionate, devoted and innovative Credit Profressionals. We’re Here Each Step of the Way

You don’t have to worry about our material being tailored towards UK (or any other country) only, being all accounting but no actual cash collection or all theory but no practice. Almost all of our clients are SSCs, GBS and BPOs and we all worked in them before as well so we know the reality, the challenges and how to overcome them. Our team and advisory network unites a wealth of highly respected, passionate and dedicated professionals with global and practical experience.



All of you in SSCs, GBS and BPO are surrounded by Big Data. Every symbol and character on every invoice is part of it. It is a huge treasure island, but not all of it is the actual treasure. Lots of it is sand that you have to be able to navigate through to find what you are after.

It takes highly skilled individuals to interpret that data and communicate with internal and external clients to convert it into a positive cash flow. You need to know how the business works, how do your client operate, what’s relevant and value-adding and what’s not, be able to recognize the patterns and know how to act on them.

It is something that will come with 5+ years of experience or a fraction of that time spent with us.



Callisto Grand was founded in 2010 to address the significant knowledge gap in Credit Management within Shared Service Centres (SSCs). Although SSCs aim to be Best in Class, there was no widely recognized standard for success or specific development programs until Callisto Grand emerged.

Mark Harrison, the founder, brings 40 years of experience as a credit professional, with deep insights into operational requirements and a solid track record. From 2005 to 2012, Mark played a key role in establishing the O2C infrastructure for two SSCs in the Czech Republic, while also earning an Honours Degree in Credit Management. His extensive research for his dissertation, ‘Credit Management in SSCs,’ along with firsthand observations, highlighted a significant lack of O2C recognition across the board.

Before 2010, there were no training programs tailored to the unique demands of the burgeoning Multi-National Shared Services sector. This led to the creation of Callisto Grand (previously CZICM and ACCEE), starting with training sessions in the Czech Republic and quickly expanding to other Central European countries, now drawing interest globally. Initially focused on Collections, it soon became clear that today’s professionals need to be versatile and well-connected.

In 2017, Professor Patrick O’Connelly joined as Director of Curriculum and has been the principal architect of the Credit Masters Level 1 & 2 qualifications. Alongside Mark and Patrick, all Callisto Grand trainers are seasoned operational business managers. Our aim is to lead SSCs to excel, using our Comparative Performance Measure (CPM) as both a roadmap and benchmark for success. The story of Callisto Grand continues.

Our Team

Mark Harrison

Chief Executive Officer

Eszter Gabriel

Operations Manager

Pavlina Markova

Academy Manager

Aleksy Matukiewicz

Member Success Manager

David Wilner

Academy Mentor

Magdalena Benesova

Academy Coordinator

John Heaton

Academy Development Manager


At Callisto Grand, we are committed to supporting diverse organizations that represent crucial aspects of our world. The 3 causes we advocate hold immense significance, highlighting the importance of remembrance, tolerance, sustainability, and health. We donate €5 to each charity.

Together, we will shape a future where Credit/O2C stands as a beacon of excellence in the business world.

Schindler’s Ark Project: Preserving History, Fostering Tolerance

The Schindler’s Ark project serves as a poignant reminder of our past and the imperative need for tolerance and respect. We strongly believe in remembering the dark days of history to promote empathy and understanding among all individuals. It is essential to acknowledge that everyone deserves the freedom to live their lives authentically and harmoniously.

Regen Innovation: As climate change continues to challenge agriculture, food insecurity threatens every part of the planet.

The Regen mission is to enable smallholder farmers to adapt to and overcome the consequences of climate change by bringing together various international organizations who are working independently on this issue.
Listening to and understanding local communities is one of the key principles. The local knowledge that a community holds is invaluable and combined with the outside scientific expertise that your donations will provide, they’ve found sustainable farming solutions that are not only within reach but can be designed, implemented and tracked.

The MS Society: Empowering Lives, Advancing Research for Multiple Sclerosis

Multiple sclerosis (MS) is a neurological condition that disrupts the proper functioning of the nerves. In MS, the immune system mistakenly attacks the nerves, leading to diverse and unique symptoms in each individual affected. Although MS is a lifelong condition, proper management, treatments, and the support of specialists can significantly improve quality of life. The MS Society is dedicated to helping people live well with MS and funding research to find a cure. With an estimated 2.8 million individuals living with MS worldwide, the prevalence of this condition has been increasing globally since 2013

The Right Choice

Incorporating these reasons into your decision to join a Global Credit Community can contribute to your professional growth, expand your knowledge base, and elevate your credit management expertise on a global scale. Whether it's on a GBS or a personal level.


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