Poor service at eastgate studio 88

Good morning, I have bought 3 pairs of sneakers at studio on the 18 Dec 2021 in one pair doesn't fit my boy, today when I was returning it at eastgate mall, I was told to produce a slip which I don't have, I only have the transaction date which also reflect the person who assisted me but still they refused to exchange for a bigger size, please help me ***

Kind regards Nndondeni