Your ISP sells you a product which they know is oversold in capacity. Instead of fixing their capacity problem they now try to get you a their consumer to not use their product (the cap limit).
The concept of TOECDN solves the distribution of static content on the Internet. NetFlix, Youtube, Steam and whatever you are using to go over your cap can and should be fixed by TOECDN.
TOECDN place the cache server as close as possible to you as a consumer - even with the possibility to have your own cache server at home!
If you place cache-servers within the ISP networks, they, as a benefit, don't have to upgrade their networks connection to be able to push out more data to their consumers.
Before anyone reply and say: it won't work, it will never work, I will make sure its not going to work, I have invested heavenly in CDN companies stocks so your solution can not see the light, etc...
I would like to ask you: How does _your_ solution looks like to be able to let anyone on the Internet to cache their content on cache-servers within a ISP?