I can tell you that I my experience you are better off walking away. I had a ton of issues with my wife's truck early on and spent way too much time at dealerships and dealing with corporate that in the end the "resolution" was never satisfying. If you are already this upset, you are best to move on. This will sour the car for you and you will likely never be happy. Even if you think you will, you will always be worrying about something else going wrong and wondering how crappy it will be to get them to fix it.No wonder why American cars sales declines year after year. This service is really bad and the honesty....no way! Never again. But I’m not done with them.
But I get where you are coming from...I think I am a bit like you...if you are sure you're right you will fight like hell. Unfortunately domestic cars seem to have more issues with the dealer/mfg relationship than others. With the Ford we spent most of our time with them pointing their fingers at each other. Dealer says they can't do work unless mfg authorizes and mfg says they can't control dealers since they are independent.
Just one example of many, I complained of a rear end clunk. Dealer can't reproduce and sends me home. So I crawl under only to find oil puking out the vent. I call dealer back and ask why if I complained about a rear end clunk they wouldn't even do a visual check and said they can't since Ford won't authorize the time if they can't duplicate the concern. I then called Ford and was told that is nonsense and that I should try another dealer. Four dealers later some of the concerns were addressed. The benefit Ford had is a huge dealer network, Buick not so much.
Good luck with whatever you decide.