Poor Post Sugery Service

We I don't know where to start, I recently did a operation through my medical aid. Everything went smooth until the bill came through, I wasn't informed that I would have to pay the Anesthetic Dr from my own pockets. Now I am being harassed by his wife calling me every time asking me to settle an account I was not made aware of. Had I known that I was supposed to chip in, I wouldn't have done the operation in the first place. Like who monitors these big companies like discovery from doing things like this to the low end citizens. No one had called me from Discovery to inform me about this or even a heads up. No one has the nerve to even inform me what happened.