Bad customer service and false advertising

Good evening On the 10th May 2019, I bought a pair of red sandals at Rage in King Williams Town Fleet Street. The price on the sandals was R139.99 and when I went to pay the cashier told me I have to pay R179.99. She said it's a mistake. I asked for a manager and they told me they have no manager. There were about three staff members in duty. Please I need my change as they totally refused to sell me the sandals for the price on it.