Rude Cashier at Mr Price waterfall mall

I am sad to report this matter, I went to Mr Price in Waterfall Mall, Rustenburg, and the cashier at the pay point was very rude. I tried giving her my receipt for an exchange and she asked me to keep it I told her she is going to use the receipt to process my exchange why does she give it back to me to? she was so adamant and rude about the fact that I keep the receipt on me and was rude and ready to argue. I ended up not even being able to exchange the item as I was told at the end of her capturing my order that the system is offline. This is the first time I had experienced such a rude cashier at Mr Price.