Stock incorrectly priced

Very rude manager, went to Side Step Benoni to buy my brother sneakers got there and there was Ellesse sneaker that was Marked down to R400.00 asked for that exact shoe got to the till and they said it's R600.00 and was dismissed with them saying it's December and people make mistakes she didn't even apologise she just said her system says it's 600. According to customer law it is within my right to pay for the product with the price advertised it is not my job to price their stock for them. This is very unfair and very bad or poor service i simple i am sorry for your inconvenience would have gone a long way not make up for anything but still.