Gross Incompetence

In November last year I was diagnosed with malignant melanoma. The doctor referred me to a specialist to have the melanoma removed. Total bills for the procedure and testing were around R15k. All claims submitted to Discovery were rejected. I then complained. I was told I must register for oncology benefit then reclaim. I registered. Then reclaimed. Everything rejected again. Then I got my pa to contact discovery. Literally hours later on the phone and multiple times being cut off, transferred to multiple people I eventually got paid R1854 of the total claim. I wasn't happy but moved on. Now I get a phone call from Discovery saying I owe them money and they sent me correspondence regarding the money. The money I owe is apparently the R1854 they paid me... I checked my correspondence and there is absolutely no mail. Only correspondence I have is what they sent me after the call which is just a statement with absolutely no explanation. My pa will now spend countless hours trying to resolve. It wont be resolved based on my experience from them, and they will hand over to a credit bureau which will give me a bad credit rating. All because of Discoveries gross incompetence.