The customer is always wrong here

I bought cupcakes from Pick and Pay Robertson which was marked on the shelf as R36.99. After I got home i saw I paid R59.99 for the cupcakes. I took the matter to the owner after which I was told it would be investigated. Someone phoned me from the store to say that the expensive price is the right price. I disagreed that this was the price on the shelf but was told once again that they need to 'investigate' . I searched for one of the owners at the store after which she told me that I was wrong and the price is R59.99. Shocking that the customer is always wrong here! The same thing happened one day after this. Different price at till and on shelves. Please check your 'trillion' lines and scan the products at the right prices. You are robbing us!