Fully agree on the MOP thing, but i have no patience for ill equipped service blokes - they get the callout fee for that late nighter - and get a good rest the next day, meanwhile someone else goes back and actually fixes the problem. If it needs an MOP they can go get one from a wholesaler - no matter what the time of day!

Also agree on getting someone else to engineer your installations, they are only half a mechanic if they can't select their own gear - nobody's asking them to design the coil - just pick the right one for their customer.