Can't exchange without a receipt

I went to Mall of Africa yesterday around 19h00. I went to exchange clothes that were bought for my son as they were small. I had no receipt with me and I was told the account holder should be at the branch. Now the father stays far which means my son will be without winter clothes. Did the same at Woolworths and had no issue. I offered to get them the receipt via whatsapp and they refused. The clothes had tags.