Total Sports worst ever!

I ordered a pair of downshifter 11 via online as it was going for R899. When I checked I accidentally pressed the wrong side so I called in and asked them if they will do an exchange for me at the same price I purchased it online. Today the 13 September I went to sportscene to pick the shoe up, I then went to Total sport to exchange it. To my surprise the lady said she cannot give it to me at the same price I have to fill the difference of R300 and I can't get it at same price. She stated cause of looting policy changed and I asked for the manager I kept asking but they refused to let me see the manage they were very adamant and made sure I paid the R300, they said I had to pay full price. I questioned them and argued but they were rude and did not want to give me at the price I've purchased online yet online said they will do it. I want answers as I don't appreciate what was said to me and done to me. Total sport staff seem to be having a relaxed time. When you call they don't answer the call. You have to stand n wait at the till points till they decide they want to serve you. I don't believe in this story cause of looting. What does looting have to do with the prices and purchasing online and been said I can exchange it in store for the same price. Just to avoid embarrassment and the staff adamant I paid the extra and walked away but I want my answers and would like my money back cause at the end this the only store I seen this. I've purchased online alot after looting and wen in store and exchanged it for the same price I bought it online for!