Poor service from Edgars Active Paledi Mall

I bought my son school shoes at Edgars in Johannesburg on Wednesday 30th December. My son is in Limpopo so I brought the shoes with me to Limpopo only to find that the size is big, I bought size 13 and it was big so I went to Paledi mall to try and exchange them. I had lost a receipt and when I get to the cashier he said he could not assist me because I need to have a receipt. I was really taken aback by that because I've returned items with no receipts at Edgars and they'd assist me. I decided to buy othet items and while we were paying another guy who works at Edgar's active came, I didn't quite catch his name but he told me to go get the size that I want, and I went to take size 12. So as he was about to process the exchange he says to me that he cannot exchange the shoes because I bought them at Edgars without a box and the ones they have at Edgars active has a box. He then told me that he cannot assist me because of a mere shoebox, but the shoes were bought at Edgars.