How to market a single platform for logging and tracking service complaints for multiple companies

We have a platform (app-based) called Simply C2 which is meant for our CRM clients' customers to log complaints - directly log complaints in the connected CRM account of our clients. It is free for the end customers. Our experience has been that our CRM clients see this platform and want it customised and rebranded for their own use. This gets us additional business but something we are not happy about. We would rather everyone simply used the platform. Why? Because, that ramps up platform usage rather than us having to maintain multiple code forks. Any ideas? What should we do?