Discriminated at Mr Price due to unfair pricing

On the 14/03 we visited the Mr Price at Sandton, my fiance' purchased a polka dot top. On the 22/03 we went back to the store to exchange this for one size bigger.<br> We then noticed that the price was different. We queried with the teller who queried with her supervisor who queried with the \store manager". We were then told that due to it being a bigger size we have to pay extra as this is Mr Price policy. The description of the item is exactly the same"