My mum recently experienced the same.
The previous owner of her house owed loads of money to some mail order company. The bailifs were now involved. Mummy contacted the company who the money was owed, not the collection agency, and asked them to help her resolve the situation - fortunately she could point them in the right direction to help them locate the previous owner.
The nice lady she spoke with believed mummy was genuine and called off the bailifs.
On the other hand... have you got Mav's number?!!