to CableForum.
Sounds like whoever entered your details on the system put you down for the wrong speed. I know you upgraded, but it sounds like your modem didn't recieve the "hit" with the new speed.
If you phone Customer Services, they should be able to get the system to re-send the hit (or find out what happened).
Failing that, a number of members are Customer Services people for NTL, perhaps one of those will read this thread (I personally can't help, I don't work for NTL).