Sorry to hear this.
Only thing I can think of is to take it to one of those indie shops, not tell them what the dealer says, and see what they come back with as a diagnosis.
What if it's as simple as a loose connection? (Not saying it is, but who knows, most dealer techs only use paint by numbers approaches, and don't think beyond that.)
I'd want an independent second (or third) opinion before shelling out that kind of money to a dealer.
Good luck!