Medicare and preauthorization

I am having a 3 day trial for spinal neurostimulation implant for my severe nerve damage pain from my BMX with  node removal.

I called Medicare to see if they will pay. They couldn't tell me. I was instructed to call the clinic.Medicare refused to say if they would cover it and kept telling me to call the clinic. The Medicare representative told me they will decided who will pay for it after the surgery.

The surgery is obviously very expensive and I don't want to be caught in a battle and/or get stuck with the bill.

I called the clinic. They refused to tell me if medicare will pay for it. The clinic representative said she "has heard" that they pay the standard 80%, but refused to tell me if they can get pre-authorization from Medicare.

What can I do so I am not caught in the middle and stuck with the bill?

Has anyone had this problem with regular Medicare (I don't have an HMO or other insurance because I am on disability and they charge so much for the monthly payment, it isn't worth it. People on disability have to pay a higher rate than the elderly who are not disabled for the extra insurance.)

Thanks if anyone can shed some light on this for me.

Cinnamonsmile