Maybe you didn't understand; I feel for your dilemma. I suggest that you try an independent specialist.
I work very hard to see that my customers cars behave efficiently. It is a personal failure to me when any of my customes cars become a burden.
If you have delt with dealers since 1973 with results that leave you distrustful you haven't had a good relationship; I'm sorry. There are good dedicated people in this trade as in all trades. They even exist in dealers. It may be that the impersonal relationship maintained by changing workforces in most dealers leaves you on continuous unfamiliar ground.
I happen to know a lot about this business; mainly from being in it so long. I can give you a single answer to a current problem and make a small difference, but if I give you an idea of how this business works that helps you have confidence, I have really done something. I might not be right but it is a point o view based on thirty years in the trade.
BTW, I probably don't know a technician, skillful in his trade, that has any interest in false documenting his work. Anyone compitent enough to falsify to documents doesn't have time; his talents are too valuable.
The problem with so many consumers is they see our trade as something akin to digging ditches or laying bricks. Just reproducable work. Probably only one out of ten techs are true diagnostic technicians. It will always be your job to find them and recognise when you have!
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician