These people are calling to collect on a 3 year old magazine subscription (of which I have never seen heads or tails). I told them that I will bring suit if they continue to harass me. What research I have done has lead me to this advice:
Don't answer their calls. They are trying to intimidate you into paying a phony bill. I don't live at the same address, I don't have the same bank account. They got my number only because I have used this number for many years.