My tactic was to appear (!) incompetent on a computer, then when he had talked me through it step by step nearly to the end say "Ah, its too late now, I have to clock off, I will just pass you over to my colleague... and start over.
The third of my colleagues was a bit of a rambler...
"OK sir, press the windows key"
"Oh, I did my windows yesterday. It was cold putting my hand in that bucket. It was wobbly up there on my old ladder, I really should get a new one. I did look at them down B&Q but they didn't have the folding ones because mines is a bit of a pain to store. I remember
Maplin had some folding ones so I was going to walk round, but my ankle started hurting, with each step it was going click, have you ever had that? I guess not you fella! Now, you said something about making toast...?"
He sounded a bit like Alan Bennett.