General Motors complaint: NO answers as to part availability and no help supplying alternate transportation

My vehicle was involved in at no fault accident on August 1st. The vehicle was taken to a Buick collision center on August 3rd. Other party in accident covering loss. Within a couple days the repair place finds that part is not available, on back order but not sure if they even have the part. Calls to GM have been almost daily but still no new information. The insurance has provided me a rental for 42 days but in 3 days the will no longer provide. It is felt GM is responsible since they are not able to supply the part. I have called everyday seeking help in getting a rental and checking to see if part is available yet. All I get is a run around and no answers to anything. Even a bit of an attitude problem. First, If you cannot provide this part..SAY SO, don’t keep stalling. And to make matters worse you no longer make this model. It is a 2017 Cascada! I have no other transportation, They need to take care of this!! And no I should not have to pay out of my pocket. I have always complimented and wanted GM but I think I am finished. I don’t think GM cares I would like a response!!