Union Hospital Account's Department Asleep

I went for a gastroscopy the 25th of November 2017 and had been paying off bills which my medical aid didn't cover until now, which I paid every month with no problem. I have a good credit record and always pay my debt.

On the 25th of April 2018 I received a final demand letter via email from Union Hospital saying that I owe R1628.15 from Lindy Mogemi. I had no idea I owed this as I had moved on the 1st of December 2017 and therefore didn't receive any letters in the mail stating that I owed this. Why the hospital didn't just email me to begin with still baffles me, but in all fairness I still phoned and made arrangements with Lindy Mogemi to pay off the R1628.15. She told me that the hospital only allows a 6 month pay off period which I agreed to. This means that the account would be settled by end September 2018 once I do the first payment end of April 2018. She said that she would make a note on my file. I have therefore paid R271.36 every month since then where my last payment was done 1st of August 2018. I also sent proof of payments during this time.

On the 5th of July 2018 I received a Credit Bureau Pre-Listing Notification letter via email from Candy Arendse saying that due my lack of response regarding my account that is in arrears if I do not settle the account by the 4th of August 2018, my account would be listed. I then proceeded to send her and Lindy a mail saying that I have arrangements to pay off the account and will not be able to settle the account as I do not have that kind of money just laying around.

Today, 14th August 2018, I received a letter AGAIN from Candy Arendse saying that my account has been listed due to, and I quote, "We refer to our Credit Bureau Pre-Listing notification letter sent to you via post, email, dated 05/07/2018. We HAVE NOT RECEIVED any response regarding your outstanding account with Netcare Union Hospital." This is a lie as I contacted Lindy by telephonic means and was also in contact with both of them via mail regarding my account.

I want my account to be taken off the Credit Bureau listing as I've always had a good credit record and have never not paid my debt and I don't want to sacrifice my good record for people who are asleep. I find this extremely unfair and infuriating. Can someone capable please assist?