Ruined wedding day

I purchased a platform sandals last week the size is a 7 however it can fit a person that wears a size 4 I sent my daughter for an exchange at Mall of Africa ,the crazy part is she got there and she was advised that their returns policy doesn't allow returns on sale items.We were provided with head office contacts we called them and spoke to Sphiwe he agreed that since my child is at the store they will finalise the exchange with the store.She waited there while they were checking for a size 9 for about an hour upon finding it the said the system can't proceed with the exchange.The manager of the store and their colleague Someleze didn't assist with anything.Since we're here what am I supposed to do with the meniture shoes ?