price on tag not honoured

On Saturday morning I went to this store and saw some Oakridge shorts that I liked,I proceeded to the till to pay the shorts were priced at R69.99 with the red sticker that shows the item has gone down.They had gone down from R99.00,when I paid I was charged the original price less 20%in store promo.I queried this as I was expecting to pay the red sticker price,they told me that the price must have gone up.This is clearly a misrepresentation,and I requested to speak to the manager,she came and told me there is nothing she can do but refund me my money and take the item back.This is not the first time this has happened other stores honour the price you saw on the shelf or on the price tag.I am disappointed at the way Mr Price treats it's customers.