Billing and provisioning

Hello Here is a the scenario we want to implement :- 1. User pays for 10hrs of internet access. We set the Max-Monthly-Serssion to 36000. We want to verify the number of seconds used and left for each user on a daily basis. The results should be mailed to the ISP admin and a mail sent to each user concerning his usage. When his balance is say 500s, he is requested to recharge his account. We are using Freeradius as AAA server. We are not using any databases. Can anybody recommend a script or open source package that can do the above? We need to urgently implement the above. Regards M