Cannot get Pre Authorisation for a hand operation

I have been trying to get approval for an operation on my hand. The disease only affects the hand, but Bankmed say they only cover this in the ankle and will not give me pre authorization. I have sent the Doctors quote 3 times, but Bankmed say that they did not get an attachment. When I phoned Bankmed, the assistant was very helpful, but as mentioned Bankmed say that Dupuytrens syndrome is only covered for the ankle, and I guess I will make history as the first person ever to suffer Dupuytrens in his ankles. It is unacceptable that a simple process of getting pre authorization has become so time consuming and a waste of so much precious time. The worst is that although my membership pays the salaries of Bankmed staff, when I hit a wall and request to speak to someone higher, I am informed that they cannot do that, so you get stuck with no way to resolve the problem and you have a booking with a surgeon, a hand the****** and a booking at the hospital, but there is no way out of the spiral. It is very simple Bankmed, listen to your clients, don't block them