Unfair claim from Dr Yamba and Discovery

I was admitted on the 8th of July 2022 and had to have an emergency surgery on the 9th of July 2022. Payment options were never discussed with me , I was under the impression that my medical aid plan would cover all costs with co-payments, with my unlimited hospital plan. Now I am receiving a bill from my then anaesthetist of R22 226,20 Co-payment. They should have made me aware of the co-payment so I could plan accordingly. The hospital ( Arwyp) and anaesthetist ( Dr Yamba) are part of the discovery network. Dr Yamba say’s I’m liable for the amount discovery did not pay which is R 22 226,20.