FNB and DMC did me wrong.

I would be very much happy if FNB keeps track of our payments and the discount offers we get from debt collectors. Now here’s my story I was handed over to debt collector DMC yes the agreement was to pay R560 every month then at a later stage I got a 30% discount which I agreed to pay the remaining balance and was sent settlement letter that means I do not have anything debt with FNB. Fine few weeks and days after settling the account I was told the account will not be closed. How is that possible if DMC was the one handling all the transactions. This is ******* at another level. I will have take this further to NCR