refuse exchange with slip and item not tempered

I would like to lay a complaint with regards to an exchange I wanted to do a day later, Sharon told me I could exchange the item because it has been a day later and I had the proof of purchase. The manager of the store then refuse to exchange or even give the money back which wasn't even the case. I bought the wrong item just needed it exchanged the item was not tempered with, Sharon then gave me an attitude of sort which I was not happy with I have been doing my shopping at this branch for years and never have I been treated in this manner by management or even the staff, so could you please sort this out. Totally disgusted with this checkers in Parow mall