Yes it could well be, this happened to me. Who did you get your credit report done by? One I had a while back showed everyone who'd lived here and even connected me with owners of houses I'd sold a long time ago - I had to write to the credit reference agency and explain that these people were nothing to do with me, and have them removed. Contact the people who sent you the letter (they can't stop calling, but you can ask them who instructed them, so you can explain that you are new owners and the debt is not yours, then they can call off the debt collectors).