<PRE>i had the same nightmare problem. you need to tell bt so they can take it off. tps takes 6 months to work sometimes. i changed my number, and stopped witheld numbers contacting me.</PRE>
I've just taken a look at the information under 'Directory Services' in my phone book.
Full contact details for removing a phone number are given. I won't bother quoting them here because, underneath the main information, there's this sentence:
"If you are a non-BT customer, please contact your service provider".
So, in answer to your question: No, you don't contact BT. You should contact the company which sends you your phone bill.