If I left things to the dealer I would end up with a lot of faults that don't show up on their diagnostics or that they pass off as normal with an amg. It has spent half it's time with them since purchase already so whilst that approach would be ideal, in practice it can be more painful. All the faults so far have turned out to be real problems despite initially the dealer returning the car to me saying it tested ok. I just want to enjoy the car. With stop start they charge the battery then say oh look it works. One short journey later, no stop start. During the last phone call with them they said that start stop only works 5 times in one journey, what a load of BS! Completely irrelevant too since mine doesn't operate once. So because I'm technical(not with cars) and because I don't fully trust them now, and because I want to resolve things as quickly as possible i'm trying to get more information. Reasonable?