FreeRadius Customisation

For the following work: I have advanced with the develop to assign credit to a prepaid user in daloradius, I have finished the background script and the database structure, it module does not work together the daily, monthly and yearly quotes, it works when the attribute "Plan Recurring Period" in plan configuration is assigned to "never", so, the script check if the Period is "never", then the script query into the new table looking for the credit available for the username if the user has credit then the user can commonly connect. When the user paid more credit, the system will calculate the traffic available and it will extend the expire time for this traffic. is that right? you could chose the expire time for the last charge ( 1 month, 2 month....N month). I have to finish the web interface to add the credit to the user in daloradius.