Minerva had the annoying habit of asking for the end user to email over a copy of their sales receipt to them. This was on Sharp and Servis Service work. It was annoying to say the least that when the engineer attending can view this information from the customer.
Repairtech on the other hand were very brusque and rude when reading the riot act to the customer if the appliance has been abused (blah blah blah) that the call would be chargeable. As a retailer, I got loads of complaints about that!!