Transaction went off card even thou the card machine said system malfunction

Hi I swiped my card at a store(for R51.98) last Thursday (27/01/2022). The card machine said transaction failed due to "system mal****ion". I then paid with my other Tymebank card which worked and went home. The next day I noticed the transaction had also went off on my African Bank card. So I had been double charged for the goods. I broght the matter to the awareness of the store. They said I should also make you aware. Why is their no feature to dispute a transaction on the app ? I have to choice but to approach you via Hello Peter over this incident.