I used to do the dealer servicing run, simply made best use of my time and effort until I found they were using 1st year apprentices and not completing the scope of the schedule and charging me for it. Happened twice, then cut them off. They howled like 'unfair, everyone makes mistakes etc' well compensate me then, Nope, so goodbye. I have a local guy who does all of my major stuff and he is very thorough, looks for problems etc, happy days.