Good service but shocking accounts issues

I had a very good experience in hospital with Life Healthcare Wilgeheuwel, for a routine colonoscopy. It all went well and the staff were nice, until it came to settling the account. The trouble started when I was given a 50% discount on my co-payment (R4,300) when being admitted on the morning of my procedure. I paid this immediately (R2,150). Later I received an account statement from Discovery Health saying they rejected the hospital claim. The reason was that the total fee (R3,997) was less than the co-payment amount. But they'd not taken the discount into account. Thus I still owed the balance of R3,997-R2,150. I wish they'd not given the discount, I would've paid the full amount and I would've claimed it all from my gap cover. Now, I'm trying to unravel this. The phones at Wilgeheuwel are terrible. I can hardly get hold of the accounts department - it just rings and rings. On one occasion Discovery Health got hold of them for me, and they promised to get this discount app**** and sort out the account. That was a month ago but nothing has happened. Then last week I managed to get hold of them and they promised to get it addressed. Again, nothing. Today I phoned and was told to phone the national call center. They told me I need to phone the credit controller. Her phone went to voicemail. I've left a message but I have now spent a few hours on the phone trying to resolve this over a period of 6-7 weeks. I have also emailed every email address I can find (including replying to emails where I received a statement from the hospital and from the national accounts dept) but they seem to go into a black hole. As a matter of principle I would like this to be resolved. And hopefully to identify the gaps in your processes, so others are spared this wild goose chase and wasted time in future.