Netcare Rand Clinic account mess

I got admitted at one of the Netcare hospitals in Johannesburg in January 2019 and everything was approved beforehand. After getting discharged a week later, my medical aid requests that the hospital must send the motivation as to why I was admitted. I called my admitting doctor who submitted the motivation immediately to the hospital's case manager, who in turn was supposed to update the information with the medical aid. 3 months down the line, I get e-mails and sms's stating that I owe the hospital R18 797. I follow up with my doctor who confirmed several times that he submitted what's required to the hospital's case manager. I call the case manager and she tells me that they will submit to the medical aid. A week or so later I call the medical aid to confirm if they have received anything from the hospital, and they still haven't. I call the hospital case manager again, and she was not there but someone said they will submit. This went on and on for a few months till last week when I called the hospital, I'm told it's no longer under Netcare. Today I get an e-mail from that specific Netcare hospital, specifically from Golden Maseko, about the outstanding amount and that I must pay it with immediate effect.

I need Netcare to sort out their accounts and submit what needs to be submitted to the medical aid before they start harassing patients with outstanding invoices while they haven't done what's required from them. I can't even get hold of anyone at the hospital itself as it's now under new management and nobody know anything. Should I write my own motivation when everything was submitted to them for payment? My doctor has addressed this with the hospital in many occasions but someone was just sitting there as usual and not doing their job. I need this sorted asap and all this harassment stopped with immediate effect. Do your work, PERIOD!