Jacket exchange that I had to pay a difference for after 1 DAY of purchasing it

I went to Ackermans Birch Acres Mall , Tembisa on the 19th of April 2023 and purchased some clothes for my daughter. Firstly when I got home doing fittings with my daughter , only to find a tag was not taken out of a pack of tops. Secondly one of the jackets I had bought for my daughter didnt fit her. So I went back on the 21st of April to exchange the size now I'm told the jacket is no longer on special and I must pay a difference of R40. I find this to be day light *******. The exchange should be done on the same price that I bought it for irrespective of the fact that the special was over. This exchange was done 1 day , I mean really just one day. This is nonsense , I shouldnt have been made to pay a difference.