Incorrect account balance. Failure to respond in 2 weeks.

Ref Account: ***. Edgars has failed to rectify my account balance after 2 weeks of my initial complaint. At this stage I have sent 5 different complaints to various departments (customer services, accounts department, disputes etc). On 25 November, I purchased two dresses on for R299.95 each, a white yellow floral dress and a Blue tea dress. I returned the white yellow floral dress on 3 December at the Baywest store, leaving a balance of R299.95 (I have the receipt to prove it and a witness who will testify to this effect). On 7 December, I went to the Baywest store to pay the balance for the dress I had kept. I expected that balance to be R299.95, but they told me that the balance was R599.90.I told that them that this was incorrect as I had returned an item for R299. 95 last week. They told me that all they can see on their system is a balance, no record of previous purchases or returns or dates. I would have to do an enquiry to customer services myself. This is a ridiculous system whereby the store has no means to see that a return was done last week. I then began sending a sequence of complaints to Edgars via email. All three receipts were attached as proof: My original purchase for R599.90 on 25 November, my return of the white yellow floral dress for R299.95 on 3 Dec (the slip says credit unwanted gift, paid by my husband TG Pather) and my payment of the R299.95 balance on 7 December--thereby leaving a balance of ZERO. More than a week after my initial complaint, I received an account for R329, including a service fee for not having a zero balance- which Edgar's is not entitled to. I have had no email response from Edgars to show me that there is any investigation into this matter. If by any chance I have missed any calls, this still does not explain why an incorrect account has still been sent out. I expect proof in writing that this account has been rectified. I have proof of all emails as well as receipts - as mentioned above.