Terrible service yet again

I sent my driver to return some items and had told him to put the value of the items on a gift card so I could go shop at a convenient time. The lady at the counter informed him that those items were on sale last week ( I don't see how this affects my current items as they were bought before the sale). I have shopped at many Edgars stores and it was the first time I had an experience like what I am about to tell you. As far as I know when you do a return/exchange without a slip the cashier will scan the items and inform u if the price has dropped and its on you to decide to proceed further,(I usually take what I need and pay in the difference or if its less than the value I always get the balance on a gift card to use at a later time), anyway my items were still scanning at the full price but Miss Thang (Julia) decided on her own that she knows better and made the items less 50%, my driver did not even know anything and returned with a gift card with R175 on it whereas it was supposed to be R350. Edgars has clearly ****** me. I called the complaints dept and nobody answers,eventually got through but you all are useless,even the store manager. I want my items back at full price