I was a Service Writer in a GM dealership for many years. Call 1-800 number for Ford Customer Relations. The dealership Service Manager can also request the Regional Rep to meet your friend at the dealership to actually see the vehicle and review the paperwork. There is always ways to get a higher review. Doesn't guarantee the desired outcome.
I too find it very uncommon for both mirrors to fail simultaneously. It is unusual for one to fail, let alone both at the same time. I would suspect a module or other common factor. I find the diagnosis suspect myself. Perhaps that is why it was denied?