dubious practice

My complain is about a debt collector company MBDC Inc., since they started debiting instalments on behalf of MTN, I have been receiving the same Balance outstanding on the statements each and every month or R12667.52 whilst I have been paying them, <br> when I called in to find out why there is no difference in the Balance and the consultant that I spoke to (Jessica) said I owe R1000 and some change to close my account ( of which I have recordings) and I agreed for her to go ahead and take the outstanding amount to close off my account and she must send the proof of an outstanding amount but she sent me the same statement I was sent initially, and when I called in after receiving the statement they say they don't know any consultant by that name Jessica and according to their records I have not spoken to any individual of that name and no arrangements of that nature reflects on their side, <br> <br> And I told them that they should not take any money from my account up until they resolve this and they went on to debit it, and now they keep threatening me because they are lawyers of MTN<br>