Rude cashier : Seanego Moloto Pricing

I bought a 750ml Bonaqua water bottle at a cigarette counter in centurion PnP hyper. The price was R11.49 price sticker at the refrigerator do. I paid with R50.00 and the till reflected R12.99. I then told the cashier she did wrong pricing. The lady was agitated and told me I should have told her, and I told her the price was visible and a sticker there. She gave me the change and said I told her late with that rude unfriendly attitude. I asked her must I pay 13rand for an item priced 11rand she then calls someone I thought it was her supervisor she came and made a laughingstock joined by the third colleague's they asked me in that laugh. As they laughed asked really do you want R1.50 I then told them on the consumer council rule in pricing. I don't know what made them reacted in such 'disrespectful manner. If the price is incorrect and displayed if I had R1.50 was pnp going to give me the item purchased.