I can understand your frustration, some, not all by any means, engineers like to build up their own importance by over complicating the job to justify what they charge or to hopefully receive an out of hours phone call to a breakdown they can charge a small fortune for!!
My worst experience of this was with British gas, when we built our house we were amongst the first to fit a condensing boiler. The installer knew little about servicing it and recommended we take boiler cover with British gas. Many breakdowns and call outs later we got an engineer who fully explained the problem. The condensate trap had to be flushed at every service, if not, condensate built up, boiler would shut down and the front panel needed removing to press the reset button. None of the previous engineers would do this flush, even though it was clearly mentioned in the boiler manual. None of the subsequent engineers would do it either even when asked so I did it myself as soon as they had gone. I suspect they were a bit confused as to why they never got another breakdown call out to this particular boiler.
Another problem, we have an unvented hot water system. When we ordered the boiler we specified a valve be fitted to allow the boiler to work in an unvented system. "This boiler isn't suitable for this system sir" they said at every service, they would slap a sticker on the boiler saying it was unsafe and not to use despite me telling them it was. Many complaints later I had to obtain a letter from the boiler manufacturer (at my cost £40) stating what I already knew. British gas accepted and said I could remove the sticker and use the boiler. It gave me immense pleasure to tell them " they put the sticker on therefore they would have to come and remove it" which they did , even though I'd never stopped using the boiler😁
I could go on but will spare you.
One other thing that I find curious, everybody seems to be an engineer these days, the person who does the boiler, fixes your washing machine, services your car and more. Are they really engineers? I would say technicians, but could be wrong. If called myself a timber engineer could I charge more?🤔
