I just had a 'Microsoft' call today. They're quite common, apparently.
I told him I'd call back and asked for his number, which he gave(!):
I had a spate of these at the start of the year. My answer is to tell them I run Linux or Macs. I don't) They faded away, and after a bit stopped calling
I know someone who's mother was caught by this scam, and paid for them to "fix" her "faulty system"
Bar stewards the lot of them.