Refused to accept the goods

I would like to report the Express shop (clothing store) in Birch acres mall in Tembisa. I bought a wrong school shoe size for a child, when I return it to the shop, I was told that they will never accept the shoes as it is no longer in good condition. The shoes are still in good condition and not torn or anything of that sort. The slip declares that the goods can be returned within 30 days from date of purchase. I bought the shoes on the 14th jan 2020. I want my money back from them and also if possible. Store manager: polokeho Regional manager: Zaid. Store number: ***