Hi, you need to visit the consumer action group forums, they have folks on there who are going through the same thing.
In the terim, do send them this letter and hopefully it should get them off your back:
Dear Sir/Madam,
Harassment by telephone
FORMAL COMPLAINT UNDER THE CONSUMER CREDIT ACT 2006 COMPLAINTS PROCEDURE
Account Number:
I am writing in relation to the quantity and frequency of telephone calls that I have received from your company, which I deem to be personally harassing.
I have verbally requested that these stop, but I am still receiving calls.
I now require all further correspondence from your company to be made in writing only.
I am of the view that your continued harassment of me by telephone puts you in breach of Section 40 of the Administration of Justice Act 1970, and the Protection from Harassment Act 1997.
If you continue to harass me by telephone, you will also be in breach of the Communications Act (2003) s.127 and I will report you to OFCOM, Trading Standards and The Office of Fair Trading, meaning that you will be liable to a substantial fine.
Please treat this also as a formal complaint, and send me a copy of your company complaints procedure.
Be advised that any further telephone calls from your company will be recorded.
Yours faithfully,