The same is true of many professionals we all deal with. Doctors, lawyers, banks, stock brokers, computer pros, etc. We don’t know exactly how they do their job, nor do we have a good way to monitor if they are doing it correctly or not. Common sense dictates we rely on personal recommendations when we select each those professionals, b/c we trust the person making the recommendation to us, that the pro has done a good job for them. We don’t buy medical textbooks to study before we go to the doctor. We just go to the doctor. Maybe we’ll read an article in Reader’s Digest about the topic first, that’s about all we have time to do. If the pro we select doesn’t do a good job, or overcharges us, or lies to us, we’ll fire them and hire somebody else. No reason to treat vehicle repair pros any differently.
So if you’re not satisfied with your auto repair pro, ask your friends , co-workers etc who they use, interview a few shops from the list, and choose a new shop. Try not to use the new shop for some emergency job the first time. Use it for something routine, like an oil and filter change, change the windshield wipers, something like that. Give yourself an opportunity to build up some confidence towards the new shop. Meanwhile the new shop owner will be building up confidence towards you, and getting to know you, your vehicles, and your priorities.