incorrect pricing

On the 29/11/15 I went in to the sunglass hut store as I was attracted by the 60% off sign displayed on their window. I looked around and found a pair that I like at a right price of R1140.00 with a 60%off sign on the tag. I being a normal shopper did my calculations which gave me an amount of R640.00 or so. I then took the item and proceeded to the pay point, to my surprise the cashier by the name of Tebogo told me to pay R910.00 which confused me, when I showed her the price she told me that the price displayed was already marked down, I requested to talk to the store manager and I was referred to Judy-Anne who is the area manager and was not available at that time, she then came to my work place and offered me a 30% off instead and I refused based on the price tag I saw. 30/11/15 I then wrote an email to their customer service department [Email Removed] to try and resolve the matter however till today no one has come back too me.