Creating a bad name on my credit health

Hi I've been with Amarican Swiss for a long time had good business at first, I always go in store to make payment direct, then I lost my job and had about R223.74 left to pay, I notified them and said I'll come pay as soon as I get job and settled. So after 3 to 4 months I got a job and waited 1 month and went to pay the full amount. The lady helped me and I also asked how would my credit me open again, she rep**** that I would have to buy something witch is fair. But till about this December I get a mail and a call saying that I was given up to DMC credit and that I need to pay that amount, so I taught how is that possible and went last month payday (January) to the white River mpumalanga branch to confirm, the lady said that I am clear, so DMC phoned and I told the how and why and that I think they are spam and they must sort it out with Amarican Swiss White River because I paid them. And nou I can't even make a loan on bank or so they are blocking me