Very very Poor Customer Service

After this experience at Edgars Cape Gate I will never shop at this store or any other Edgar's again. About 4 months ago I bought for about R3000. The following day I gave back Clothes' of about R 1300. Up and until this day this has not been rectified on my account. According to my calculations I need to pay about R300 per month on my 6 Months Payment plan account. I am now in arrears because of only paying R300 every month and probably getting a bad credit against my name which is not my fault but Edgar's fault. I have no idea what to do in order to get this sorted. This matter has been handled by various different people but no one can sort this out. Pathetic