I received one of those calls this morning. First off, I run Linux, so it was obvious this was a scam. After the guy started his spiel, I told him I had to go to my computer and put him on hold for a couple of minutes. Then I was transferred to the "senior tech", who wanted my to press the Microsoft key & R. After telling him nothing happened, he tried to get me to enter a URL in a browser, In the middle of this I told him I had to go to the door (another couple of minutes down). When I got back, I asked him to start over. I then humoured him a bit longer, before telling him that I run Linux and knew his call was a scam. I barely had time to say that when he hung up for some reason.