Fedhealth co-payments that are not discussed with member

I have never really had issues with fedhealth till date but this is the most frustrating thing I ever had to deal with, my son was admitted in hospital 04 February we were discharged 05 February 2024. So I get a call from Netcare billing department saying I owe them 7500 the medical aid said there is a co-payment for a procedure I was confused as there was no procedure done on my son, called the medical aid and they told me the hospital submitted codes for a procedure and I must send the email with statement showing there was procedure then they will resubmit it went back to hospital and I was told the codes are correct his words were medical aids should tell their clients the truth. Went back to fedhealth and was put through to authoritarians and I told the co-payment for son is because he had gestro issues and that an email was sent to me advising me of the co-payment on the 04 February 2024. I told her I didn't receive it I went back checked it found it and forwarded her the correspondence from fedhealth and the authoritarian letter said nothing about a co-payment, after that her and team leader now changed the story to say the hospital updated after we were discharged that's why I have to pay. Yet I was never informed about this at any stage of my sons hospital stay in writing or even a call or sms