Receiving goods at the price that is advertised

On Monday 19 November 2018, we wanted to treat the kids to ice cream at KFC Lifestyle centre Tzaneen drive thru. The menu board clearly showed the soft twirl as R4.90. We ordered 5 soft twirls and I gave the R25 to which I was informed I short R5. I questioned the lady as the board clearly showed the price as R4.90, to which she said the price is now R5.90 and they must still correct the price. I demanded to get the ice cream at the showed price but eventually took my money and bought ice cream at Steers at the advertised price. Surely it isn't to much to ask to get goods at the price advertised??