I don't know whether this has come up before, and even if it has, it's probably worth re-warning people.
I've just had a call from a friend, and she told me she had been having some problems with her computer, and today she had a call from an Indian sounding man who claimed he was calling from Windows Technical Services. He seemed to know all about the problems and said he would fix the problems if she followed his instructions, which she did, believing of course that he was genuine. I imagine that was how he took control of her computer. He then directed her to a page to fill in her credit card details and wanted to charge her €129. She then told him she wasn't going to pay him and put the phone down. A few minutes later she had a message come up saying they were unable to run a scan and they had f@cked her machine. And then she discovered that they really had.
I think the message is: don't answer calls from anyone claiming to be calling from Windows. As someone pointed out, Windows don't do that.
Happy Christmas everyone, and a good New Year.