Discovery wont pay & doesnt bother to investigate

I delivered my baby girl via C-section on 6th October 2015 (auth no. ***4). We then had to move medical aids due to my husband starting a new job and the only amount outstanding with Discovery (as advised by them) was an amount in the region of R500 which was due to our savings account being used up. In January this year I received a call from what seemed to be debt collectors informing me that I owed Discovery an amount of R37 000 for my authorised C-section! This was the first I had heard of this. My husband and I have tried countless times to try and phone Discovery in order to resolve this issue to which they say they will call you back and never do! Everyday this is hanging over our heads. Before joining my husbands membership at Discovery, I was a member with Discovery for years in my own right...hardly ever using my medical aid but when you need it and they need to pay then this is how they treat you! I am greatly disappointed with their service and lack of response in this regard including how they so easily hand you over to debt collectors when it was clearly their responsibility to pay the account.