Online voucher and account limit

Can someone help with this?, I bought stuff at mrp home online using a gift voucher and I received my stuff. Later that same week I went and paid my account which has a credit limit of R3200 something, I paid R1000. I was surprised when I only had R11 to spend after paying since it was only R625 due. That means I paid more than I was supposed to. I called from the store one of your online consultant said that my voucher was canceled and then the money I paid went to the purchases I made! She then promised that my voucher will be reactivated. But that did not happen, I called more than 5 times & each time I am given a different story and promises. I even have emails. I have had this account for many years and this issue is very disappointing