I had a recent bad experience with one of our local dealerships.
Let me start by saying I have a good friend who is a mechanic and he does almost all of our work. However, there are times when he feels something is beyond him or requires specific knowledge from that manufacturer and he will recommend that we go to a dealer for that one issue. So, that is what happened recently after our vehicle repeatedly died while my wife was driving it. The engine light popped two codes, one for a spark plug misfire and a second for the cam shaft sensor. My friend read the codes and began to check on the cam shaft sensor because we had run into that problem about a year ago. With his travel tool kit he didn't have the right tools to fully remove the cam shaft sensor, but based on our history with that engine code and all that is involved with that specific repair he suggested we go to the dealer.
I took the vehicle to the dealer and reported everything to them. The codes had been cleared by my mechanic friend so they couldn't actually see them, but I had written them down and described everything. They said they would fully check it out and let me know what they recommended. Now, keep in mind, the dealer charges a $115 "diagnostic fee", but will waive the fee if you authorize any needed repairs. It took them 3 days before they could even look at the car and when they called me they said they couldn't replicate the problem or get the engine codes to come "back on". They could feel the misfire in the engine and so they recommended changing all the plugs, wires, and coils, and doing an "induction cleaning" to remove any buildup in the system. The price for all of this work would be around $850.
I told them I was very worried about the fact that they failed to mention the cam shaft sensor as that was my primary concern. "Well, we can't get that engine code to come back on so there's nothing we can do" is what I was told. I asked the service manager if the mechanic/technician had inspected the part. My personal mechanic friend had told me that at times the sensor can develop a crack or sometimes the part that connects to the sensor on the underside will wear out and not make the appropriate connection. He said you won't really know exactly what is wrong until you take those parts off and truly inspect everything. The service manager's response to me was "we don't do that." You don't do what, exactly, I asked? He said, if I wanted them to actually look at the parts to see if they are faulty then I would have to pay the labor charge ($135/hour) for them to take them off and inspect them. What!?! I told him that's what I thought I was paying the diagnostic fee for; so they could actually diagnose the actual problem with the vehicle. "No sir, the diagnostic fee is for us to read the check engine light and follow the steps from there based on the recommended service or problem". I explained calmly that he and I had very different definitions of the word diagnose and that if I was paying for them to tell me what was wrong with my vehicle that I expected that would mean they might have to actually check a few things out on it.
In the end, they waived the diagnostic fee and I picked up the car without having any work done. Another friend, not a mechanic, but knowledgeable about cars, and I worked together to change the spark plugs and wires on our own. My cost was about $75 for parts. When my usual mechanic friend is available, had an unfortunate death in the family, he is going to do the induction cleaning. We are just going to keep an eye on the cam shaft sensor and see if that engine code pops again. Two of the six spark plugs were really bad/worn and so the vehicle is running much better. It has not died, since we did the "tune up" ourselves and my wife actually drove it over 600 miles on a road trip this past weekend.
Sorry about the long story, but to me it highlights a real problem with the kind of work that is being done by the local dealership where I took our car. Troubleshooting is essential to quality diagnosis and repair and is a primary part of good customer service. I am blessed to have knowledgeable car people in my life who are willing to help me out in situations like this. For the OP, I would encourage talking to friends to see if you can find someone/anyone who might be able to go with you or give you some local support.