Fredrickson International phone calls

Hi, I'm being contacted frequently by FI and think that it's bogus.

They say that it is to do with a BT account but won't tell me anymore until I confirm my address - which I'm not going to do over the phone. I told them to send me anything they wanted to discuss in writing. The man I talked to yesterday said I should have received letters that I'd previously asked for but I haven't. He said another was in the post. My guess is, someone will ring back in a few days and when I say I still haven't received any, will use that as another way to try and get my address.

I should point out that I don't have a BT account. I had one years ago in my maiden name that was paid by direct debit and paid in full when I cancelled the account.

I have also used the Experian credit checker thing and have the maximum score of 999.

Any ideas what else I can do to stop them calling - don't want to email or write to them as this may give them more of my personal information!

Thanks in advance - and sorry for long post!