Possibly misunderstanding or incorrect information given by the cashier to the customer

Beginning of this year I finished paying my Edgars account of +- R11, 000. I did not take anything on account since then. Last month I received an sms saying Edgars is missing me and they give me a voucher of 50% on my next purchase. I go to Edgars store in Canal Walk and purchase for R7000. I tell the cashier that there is more things I need but they do not have them in Canal Walk. The lady said I can take other items and excahnge them with the ones I want in any other store and I did take them. The next day I decide that I want to swap some of the items for my kid and I did that by going to Edgars in Cape Gate to exchange the items for the price I bought them. When I get to the store they tell me I can only exhchange ONE item with another ONE item. That is totally ludicrous. How can I exchange R1600 item with R49 item? I was not making a new purchase I was just exchanging. Believe me I will return all the clothes I bought and close the account immediately. There are stores like H&M with quality and style at the same time.