My mother was receiving calls several times a day. They called while I was there on one occasion so I spoke to them and the calls have not occurred since...
They were saying there was a problem with Windows they had to fix and to log on etc. I said I could not be bothered, saying I did not care about the problem but thanking them for their diligence. They escalated to their "supervisor" who explained how the Windows licence would have to be revoked if I did not allow them to fix the problem to which I said that was fine, and that I was not a big fan of Windows anyway so it was not really a problem for me... (Thanking them, once again, for informing me...) He was getting angrier by the second; continually repeating I would not be able to use my computer etc. To which I explained, at length, how I thought that was probably a good thing as far too much time is spent on computers these days... I left them nowhere to go with their threats.