I haven't had any problems of them telling me that my vehicle is fine. If there is something wrong with my vehicle, I look for the tsb here. I then print it out and present it to the dealer. I have had no problem of them not being able to fix it other then them not having the part. Just walked in with the radio buzzing tsb this morning. No problem, the service writter was actually glad that he had the tsb. So hopefully the next time your vehicle needs to go in the shop, print the tsb for them and hand it to them.
Good luck.