Settled account still showing as inpaid

I have settled the above-mentioned account on 22/04/2021 via EFT payment and I was provided with the settlement letter. Then in May I noticed that the account is still showing and it has not been updated by the credit bureau. I queried with DMC and they promised to investigate the matter further . They came back and said that the money was reversed on the 27th of May 2021 and I immediately contacted my bank to confirm why the money was reversed because I never did. My bank confirmed that the money was not reversed and you can't reverse an eft and this was after a month after payment was made so the money would have already been gotten by DMC. So I then spoke to Mziwamadoda who understood my query and he promised me that he was going to sort it out. After numerous attempts to have this resolved I think I have spoken over to 10 consultants and they all have been promising that this has been escalated to high management. Then I finally spoke to a team leader by the name of Tsepang Mdalane and he also promised to get back to me but he never did. Now DMC has sent an update to all credit bureaus claiming that I owe them R4000 and I am behind with payments. This has affected my credit rating negatively and I can't even proceed to buy a house as I was in the process of applying for a bond. I have sent all the documentation to prove my case but nothing has been done about this so I beg you to please investigate this matter and have it sorted as soon as possible because it has affected my livelihood. Again I have decided to attach all the necessary documents to prove my case, the proof of payment ,the bank statement showing when was the amount paid, a bank statement showing that no money the May was reversed on the 27 May 2021 and also the settlement that was provided to me.