Fist of all, I can't personally evaluate the situation , so any slanderous words are uninformed and are only meant to help, not to just light some working guy up. But I am influenced by the words of a professional mechanic , nick named "rotten" , who , while cracking a beer in the kitchen of a party at a friends home , by way of shop talk, offers the memorable phrase, "some people are just begging to get ripped off". We never got along.
I would seek another shop. With that track record, it is clear they have no understanding of the problem, rendering repair without dumb luck impossible . If possible , only seek a well regarded dedicated corvette shop. Your dealership might have never worked on a C5 before, they are pretty old by now. also make sure they actually stock and sell corvettes, as it requires two factory trained corvette mechanics on staff before a dealer can even sell the line. ( I read this online) which kind of makes your now the manager is getting involved situation somewhat irrelevant, unless he is the trained expert.
that shop manager guidance story sounds like a snow job, doesn't he work there all the time anyway, or was he just too important to bother with a repeated failed repair his shop was turning out as completed, when they were actually guessing? Unless the guy has discovered some new electrical skills since you were last in, I'd say you are bankrolling somebody's earn while you learn situation, instead of buying knowledgeable, effective repair service.
I have read of people getting the regional GM service manager involved , who sometimes even fly in techs from the factory, when dealerships fail at repairs, but I really don't know how Gm feels about old cars and that level of service. I certainly would try to involve someone above the service manger you are stuck with, if for no other reason that to let GM management know how they are failing to effect repairs and abusing both your time, money, and trust in Gm service. I only suggest this because of the numerous failed repairs, calling in management after one or two mistakes, especially on an old car, would be a dick move.
perhaps a corvette club in your area can recommend a good electrical guy. I don't know the available resources in your area, but typically you call at least three high skill car places, like custom builders , restorers , places that don't have low skilled people running around doing the simple stuff, and ask for a couple of recommendations for your type of repair work. Once you have some lists of possibilities, you select from the ones who are mentioned on multiple lists, and go from there.
In my area, I know of a nice shop that is dedicated to electrical repairs only, since it is often a hard to find skill .
when I was testing local garages before dropping a major repair on them , back when I first got my C5, one guy actually bragged that their shop's electrical guy used to be an electrician in construction. As if a guy who failed at his previous job and would now be on my car was a good thing. Needless to say, the minor repair was a struggle for them, but I eventually found a dedicated corvette shop who fixed my electrical issue and the more expensive repair.
good luck. perhaps someone on this site can help. I once received, from a web post, personal help from a retired electrical engineer who was into corvettes and helping the less electrically skilled , but he expired.
