Pep Stores - Change of clothes don't want the money back i just wanted a bigger size

Bought a set of clothing for a child for Christmas it is to small all I want is to change it for a bigger size which the store in Pep stores in Sophiatown has and which I bought it from Pep stores Sophiatown I don't have the slip as I bought it in December and please I don't have the slip bought a lot of stuff over the December this is really ridiculous that because of what happened in July with the unrest I can't get help