Foschini Mountain Mill Worcester- Service sucks?

I bought on short notice a formal pants for my wife on Friday 18 June 2021. I brought it back the very next day because it did not fit. I misplaced the invoice but took the cash transaction slip with. They wanted to assist me but the store was so busy and I opted to come back during the week when it was not that busy. I went today 24 June 2021 back to sort out the transaction. The shop assistant called a lady who I assume was the shop manager and explained my situation. She refused to refund me and explained that it was company policy and that Inhave to take something of similar value. Nowhere on the transaction slip does it state that I have to bring the original. I assume that they can trace a copy of the original transaction but she just refused. Your service sucks...