JET Kroonstad repeatedly advertise nappies at \special"price and sells them at normal price."""

I wanted to buy Huggies diapers at JET Kroonstad today. They advertised it on the shelf for the special price of R159,99. When I payed they charged me the normal price of R189,99. I complained and the sales person and the manager I presume said that the special ended the day before. I asked them why it was still advertised for the special price and they did not reply. I am very dissatisfied because this is not the first or second time this has happened to me. It is actually the 3rd time. I must pay more money because people neglect to do their job (removing the special price advertising). What about my consumer rights?!