Denied exchange

Good morning, I write this message as a very disappointed customer, I bought school shoes from Ackerman and now I have miss placed the receipt, I went to do exchange of a size to one of the local store, Diepkloof square and the manager by the name of Cordelia refused saying their policy states that they do not do exchange if you don't have a receipt and that only applies on school uniform. The shoes still have tags, I asked her what is the purpose of the barcode? isn't supposed to be unique and be able to scan to check if the item was bought at Ackerman, she could not answers me but she kept on saying she cant assist she wants a receipt. The disappointment I had on my face, my question is what must I do with these shoes as they don't fit my child and I need them as the school re-opens on the 17-01-2024. I really need help regarding this issue. I don't want a refund all I want is exchange the size.