Had the same a few times and despite being on TPS, here is what I did when I got really fed up, you need some time to spare though:
- get whoever answers the phone to ask them to call back as "the person you need to speak to" is absent, if it's myself I do it anyway, even better give them a specific time to call.
- do this as many times as you can, I managed to get them to call back 6 times in a week
- when I finally had time to play a bit, just pretended to be totally IT illiterate and follow their instructions but give them totally nonsensical readbacks, same style as in Cunliffe's post, had them to restart from scratch as many times as I could, obviously never ever did what they wanted me to do, just pretended to. Threw in a few fake PC freezes and had them to wait for it to clear as long as possible.
Last time after over 30 minutes the caller totally lost the plot, she got so confused as to no longer know what to say, totally ruined her script, I was in stitches before she gave up and cut the call. Never had another call since!
As an option if lacking time, when you ask them to call back you can always give them the landline number of your local police station, trading standards, Pc repair services, the options are almost endless.
If you have a mate in IT who is up for giving them a hard time even better, you can get them to call him/her and do all above at an even better level.
Insults brush away on that lot, just play them at their own game.