We are a german IT hosting company serving hosting solutions to customers. We already have a (very, very old) customer administration system with an admin-backend and the frontend for customers simply based on PHP/mySQL. Customers can manage their personal data here, set and modify billing details, manage their contracts with some special features like remote control of their servers and much more (to be discussed more detailed), and much more.
Additionally that system also is our contract management and billing system. Meaning, all service that are leased by customers are stored there with their contract details like start-date, billing cycle, price etc. Furthermore the script generates invoices as pdf based on these data and sends them to the customers). Also there is reminder-system if customers are late with payments.
As initially told that system is quite old and did not get updates since ages. We are looking for a long-term cooperation with a developer doing a full re-development of what we have. Importing our current data is needed but the database structure can surely be different.
More information about our system as well as further insight about what we have can be done individually.