Worst service ever

So I have an old account with ABSA which was handed over to DMC ...fair enough last year was told that the amount owing has been reduced to R19500..as settlement amount ...made an arrangement of paying ...I paid R400 ...and was owing R19100...then coming month later R1000.......in September paid R10000....first week of Jan 2021 lady called me and told me i shuld pay told her that I wont make promises but will settle the amount by end of Feb ....she told oh really we shall see ...within the same week i went to their website and made an arrangement of R4100 and it gave me two months option with the balance of R8100.. Now im do a follow up as I need to make the payment next week...boom the settlement has been reversed ...no one told me that it can be reversed ....that's the first time in hearing that settlement can be reversed without consulting me .. I call the people all the time no one told me the risk beside that shuld make a payment and now my account is outstanding of r32000......let's not forget the is a prescribed debt ...the loan was taken in 2010 ....was interrupted ....I feel insulted i feel you guys are taking advantage and making me a fool