OK just followed up with GM.
Here is latest update.
Dealer sent car back to me last Thursday with the whole missing part saga. The dealership called me Monday to tell the unobtainable part was in. Somebody at the dealer or GM must have been working some mojo. Turns out the part they could not get was not the part on the convertible top that broke because of the spring-loaded tonneau cover that was not retracting, but the cover itself. Makes since the completely hidden top is new to the Gen6, but the other part that broke might be common to the Gen5.
I have an appointment to take the car in them on Friday at 4PM to finish the repairs as that was the earliest available time I could get off work to get the car to them before their service technicians leave for the day at 5PM.
My only regret is that if the dealership had kept the car last weekend like I had wanted, then it would be been fixed on Monday when the part came in, and I could have picked it up after work that day, instead of having to take time off work to run it over there. Combine that with some fantastic convertible weather missed during this saga, and the buttload of cold air moving in tonight.
