[MovedGoalPosts]

It's probably worth putting your complaint to ntl in writing that the service was cancelled by phone. If you want you can also follow that up with a complaint to Ofcom. You have nothing to loose.

It may also be worth checking with your bank on the exact terms of Direct Debit payments. If the bill is variable, which it must be for telephone services (even if you haven't made phone calls), the beneficiary has I believe to give you porper notice, in advance, of the amount due and when it wil be taken from your acount. Thus failure to give you notice, unless they have actually told you you wont get further bills unless the amount changes, is possibly a breach of the guarantee.