Wrong prices on shelves

I went to Checker Pretoria North last night 17 June 2015 at about 18:50 to buy sweets and yoghurt for my grandson for school which start Monday. At the sweet counter was a Checkers poster advertising 5.30 string manhatten sweets at R13-99. At till it ring R20.99 per string and I enquired but was informed that it was last week special. I paid but was not happy so I went back to shelf to check and took poster to till and show them the advertise price. She called a manager who was a white women and she was not happy to give me the advertised price. I informed her that law say you pay price that is advertised. She checked the advertised goods in pamphlet but it was not there but I insisted to pay lower price. She gave it to me but with a bad attitude. It is not my fault if employees of Checkers make mistakes. Well surely Checkers Pretoria North will not see me again if that is their employees attitude. Even worse the manager on duty attitude. She clearly do not know the phrase of \Customer is king". I also work with customers but I do not treat my customers like that. No matter what. Just thought I need to bring this under the attention of Checkers Head Office."""