What they are doing is tantamount to extortion unless you "cooperate". Let them know you are aware they are running a scam and have alerted the authorities. If that does not work, have your phone number changed to an unpublished one.
They just called me less than an hour after I got my new home phone from Verizon installed. Think about it: they randomly picked a number which had just became available. What's the odds...
Anyway the guy who called me claimed that I do not have to change utility provider to save money on my energy bill. I told him I was not interested but he was quite aggressive and persistent. But me too, so I talked even faster than him that I was not interested and insisted on hanging up. Hahaha...
Called looking for a person who once had my phone number. Would not believe me when I told them it was no longer the person s phone number. Called me a lier and said "don't play with me".