Can't return damaged shoes

Hi there<br> I bought a pair of boots at Cotton On Rosebank on Friday 1 May but when i got home I discovered they had scuff marks on the heels. When i was at the shop i had to ask a shop assistant to get this pair of boots from the store room as there were none in my size, perhaps this is why they were damaged. Nevertheless my boyfriend tried to exchange these shoes on Sunday 3 May but the cashier said she couldn't accept worn shoes- the whole reason he was returning them was because they looked tatty on the heels and scratched underneath, as if they had been used. She then proceeded to embarrass my boyfriend as though he was lying.<br> These cost me R599, so it is quite annoying that I'm now stuck with shoes I don't want. I have the receipts and tags. Pls advise me on what I can do about this. Thank you