I've just had one of these telling me that my Broadband has a problem, I let him take me through the usual patter to go to event viewer, then he asked what I saw on the screen, I told him that it was telling me that he wasn't calling from BT, he insisted that he was, I told him it was now telling me he was a telephone scammer and rang off.
I don't have BT broadband.

Anyone who has never made a mistake has never tried anything new. (Albert Einstein)