Unhelpful and inconsiderate consultants

Went to do a size exchange at The fix in Cresta, Jhb. My daughter had received this item as a gift and the size was to small. She had the receipt and the item had the tag intact. All she wanted to do was exchange the size and the consultants refused to exchange it because she did not have the card it was purchased on. So I would like to know what if the person who purchased the item is not around with the card or lives in another town, how would one go about doing an exchange. It’s not a return, it’s a size exchange, same item, same price, receipt of purchase is presented. What do we do as customers? We came all the way to do the exchange for what? Useless consultants.