MANAGER INSULTED ME

I have been insulted by the manager at Mayfield square Pieter Potgieter , I bought paint and roller set which had a price of 17.95 but when I got to the till it showed a price of 59.99 the cashier went to verify and indeed the price was 17.95 but when she called the manager he refused to give it to me at that price, what made things worse is that he insulted me by saying I might have changed the price myself. I've never been so insulted in my life, I want Pieter dealt with asap. I have been told that's how he treats his staff too he is so mean.