Without the time and resources to do it right the answer is simply no. You would have to write it on your own. I owned and operated a small ISP with dialup, DSL, and 4 different flavors of wireless. there exisits no central management tool. You're best bet is to find a decent customer front end product for billing, ticketing, etc probably a commericail product would be best. Then use open source products to monitor your network(s). Either way you will have to do some glueing together of things as state above using the APIs and scripting. It can be done, but by the time you plan, write, and implement, your production network will have changed and so will your requirements.