Took my iMac in for repair today, as arranged.
Compared to my last visit, today’s was a totally different experience. When I booked in, the Genius told me he had been doing some research into the problem. Turned out this was a known issue after all, the repair was covered by one of Apple’s Quality Programmes and so it wasn’t going to cost me a penny.
As I said to the Store Leader before I left, “I hate to say “I told you so”, but I told you so”. At least he had the grace to admit that his staff made a mistake first time around. I’ll email Tim Cook and let him know.