I have just had one of these guys on the phone telling me my PC had problems. I pretended the PC was upstairs and I only had a fixed landline telephone downstairs. Every instruction he gave me I pretended to write down and say just a minute while I go and do it. I made sure the sound of me going upstairs and downstairs was audible (just bottom tread carefully moderated) and then had a beer, checked dinner etc. Eventually I said yes indeed, event viewer showed lots of problems (as it allways will). He wanted to know what I used the PC for. Mainly word processing I said for home and work. "Internet shopping?" No. "e-mail?" No, its not connected to the internet. There was a pause then. "Can you connect to the internet sir?" Not at the moment, I used to have a modem but it broke. "When will you connect sir?". I have no intention really, what can I do about this terrible problem. "I am sorry sir but I cannot help you unless you connect to the internet." It finished with me telling him I would get a friend round.
Well it saved someone else 30 mins of this scam.
( I forgot to incorporate my original idea of indicating that I was quite elderly and eventually collapsing after all the trips up and down stairs)