Brownie to Cable Forum
This does seem to be a recurring theme within ntl that people have overpaid, yet there computers want you to pay even more money to retain the service.
The Easter break is a bit of a pain, and may mean this can't be looked at until after the holiday, but if you want to PM me some details (account number, address, daytime contact number and email) we can ask our contacts at ntl to look into this for you. They've got a good track record of cutting through the ntl red tape.