I forgot to ask - OP, did you ask them to show you the carbon buildup in each cylinder, and the spark plugs? Ideally, they would have needed to remove the intake manifold unless they have a high quality bore scope, probably with a 90-degree mirror attached. Would you know what you're looking at if they did?
I've personally seen service advisors at dealerships rip off people. One called only women and told them they needed one thing or another. He would say the mechanic recommended they needed brake pads, rotors, or whatever. What he didn't know was the foreman was a friend. When I needed something done I called him personally and gave him the car directly. I always waited. When it was done, the service advisor just pulled up the job and I paid. He never paid attention to me or my car. Too busy ripping people off, I suppose. The one time I didn't wait (too busy right after 9/11) I made an appointment through the service advisor for an oil change because I needed a ride back to my base. I still let my friend know, because he was the only one who worked on my car. I always had a case of beer in the trunk for him
So the advisor calls me and said the mechanic said one of my rotors was too thin, and it needed replacement. Of course I knew it was BS. I told the advisor to put on a new one, and it was at no cost. He asked why. I told him I just had the rotors cut with new brake pads, and if the rotor was thin it was because the mechanic cut it too thin. He told me to hold on, and comes back and tells me he rechecked and it turns out it was OK. I know he never checked. I told the foreman when I picked up my car. The advisor was fired. There's upselling, and there's out and out lying. I don't know if the owner didn't condone lying, or he was afraid I would tell people. I hope it was the former.
The moral of the story is, if you don't want to be ripped off, learn everything you can about your car. Spend the time and money to learn to how to diagnose your own car. Buy a VCDS. Buy the service manual. Sure, it helps if you are/were a mechanic but if you're an enthusiast you should have the interest in learning. Stick with one dealership, and get to know the mechanics. Find out if they have a favorite beer. I never met a mechanic who didn't appreciate a tip. There's people here that will say why should they need to, and that's fine. They're the ones who write rip-off stories
. I decided I'd rather tip the mechanic well then to need to deal with service advisors. If you don't know, service advisors work solely on commission. Especially when I want something extra, like when I get new tires I have the mechanic remove every trace of glue from the wheel weights and clean the whole barrel. That takes time. As you probably know, mechanics get paid a flat rate for a job no matter how long it takes. Prettying up your car isn't in the book.