Complaint

I had an account with this shop. I was financially struggling until my debt was up to R4020, I went to Mitchell's plain branch last month. I asked how much I was owing the store then I was informed about the above amount. I paid it off all then I asked the staff to close my account to my surprise, I was told they can't cause now I owe Lawyers whom the company handed my account to. I mean if they handed over my account why they accept cash from me? How do I know still extra 512 to the lawyer who never was introduced to me nd I had no contract with ?