Wrong advertising

KFC Daveyton mall, today I went to buy at kfc every now and then what is displayed on the menu is different on what the cashier will tell you ! You order a wrapstar box for R52.90 the cashier tells you it's R58 bcz of the coke size they only have large oky then you change your order and choose another on the screen same thing you adding a few coins where else what is on display is not there but it is advertised, I fail to to understand this!!!