Not able to exchange

I am so disappointed in pep stores exchange policy. I have purchased items on the 24 July at pep store in festival Mall. Unfortunately one of the items doesn't fit however I have lost my slip.

I used a banking card to purchase the items and when I check on my banking app the transaction is showing so I showed the cashier to reprint for me the receipt as I have a date and a time so that I can exchange.

I was told that is not possible. My question is what should happen next? Should I stay with something that does not fit and lose my money when I have proof?

This is not on at all.