Wrongful billing

At Netcare Waterfall City I was admitted for possible meningitis. The neuro booked me into a private room as I needed to be secluded from other patients. A few mnths later I recieved a bill stating I owed miney for the room as medical aid declined to pay. I called accounts, straightened the issue up and thought the matter was resolved. Months later we have been listed at the credit bureau. No letter warning us, no follow up calls. Nothing. Accounts department puts you on hold for a long time amd still no resolution.