Not happy at all

Today I had a very bad experience at Food *****s Market in Nkomo village, they priced their cakes at R19.99 and after seeing the promo I thought it's a great bargain so I took two of them since it's my brother's and I birthday month. Only to find out that the price was not correct, what ****ed me off it's when I went with the cashier to confirm the price the lady and some guy at the bakery try to cover their mistake by making me look stupid to think their cakes can be sold at that price and asking me stupid questions. How can an A4/A5 page on a stand be placed right in the middle of the cakes written cakes for R19.99 be missed and we are expected to assume it's wrongly priced?