Miss leading of discount

I bought a pants at Bluff Durban. Prize R450. A week went pass I saw that the same pants with a discount of R100. Great my shock, seeing that the very same pants I bought is suddenly R550 - discount R 100. Talking to the manger telling him that they ******** the people cause he knows that they still getting the R450 that I paid a week ago. And that there are no discount on the pants. It was a add on. And then a discount. I call head office from the same branch with their telephone, the person at head office told me I am not forced to buy, but this is strategy of discount structure followed for years and working for them.