Rude Cashier

Hi, I went to the store at Randburg Square, bought an eye pencil. When you get to the store it shows on promotion for R30.00 but paid R52.00. Then went to the store to enquire and get a refund but the cashier was very rude, gave an attitude and told that she will give my money back. Please help because now in that store they don't have a visible till machine to see the price money.. Regards, Palesa