Account paid in full . Yet i am being harrassed for monies owed. What did i Buy

I have an account with Foschini and this account I paid in full after or so I thought the full balance was paid. And I never used the account again since . After about 4months I informed i owed them money as i paid a R100 short to my surprise i could not believe it . I paid the 100 as i did not want to owe any monies. After two months i was called again and advised i owed again the same 100.00 ,and the account has been handed over and i owe now 300.00 _+ . I was surprised at this and was informed if i pay this at the store this week the account will be closed. Once again i did not want to have a bad record and argued with the consultant who advised me that i will be handed over if i dont pay this . I paid the 350.00 and thought that will be the end of it.. OMG To my surprise i am receiving threatening sms's and phone calls that i was handed over and need to pay 1200.00 something . How is this possible why do i owe more money and what did i Buy. Speaking to the consultants is frustrating and useless as all they want is money to be paid. Well i am not paying another sent .I would like a recon of my account and i would like to know what did i Buy , where did i buy it . What money do i owe you Foschini and when will this harrassment end please . Can someone give me what i want and please clear my name from owing you any moneys. I would really like to have some feedback on this after months of trying to resolve this and nothing is happening and I am being harrassed . CAN I HAVE URGENT FEEDBACK PLEASE ..