Netcare handed account over to ***** debt collectors!!

So Netcare Milpark handed one of my accounts to Colmed earlier this year. The account is for Dr Gora to the amount of R4148. I made a R200 arrangement with Colmed and have paid R1400 so far, which means R2748 is left. To my great surprise I got a final demand letter from a company called LexMed for an amount of over R4600 because now fees have been added due to non payment! I also now discovered that Colmed has been liquidated and they didn't inform any of their clients!! I am NOT going to start paying from scratch again, because I kept my part of the arrangement and it's not my fault that the company liquidated! I also will not be bul**** by LexMed who now wants me to pay almost R5000 in 10 days! And lastly, I lost my job at the end of September, so I cannot afford to pay more than R200 anyway! I have reported LexMed to the Council of Debt Collectors for their absolute rude and inefficient manner of speaking to clients. I also want to know what Netcare is going to do about this, because you are the ones who handed my account over to a ***** company, namely Colmed, who now longer exists! If nothing is done about this, I will also approach the NCR! I reiterate that I am NOT paying from scratch again, as I have all the proof of payments made since the beginning of the arrangement with Colmed.