Had the worse experience with a cashier this evening

Had the worse experience with a cashier this evening. I utilise this spar every day as I work nearby. I made a purchase with a gift card which I had no idea they don't accept by the way. When I swiped the card the cashier lindokuhle lufundo very rudely said to me is that why u hiding the card cos u know we don't accept it. I advised her I was unaware and that we could use a different card. Again she was so rude said I need to take my stuff and go because it's gone through. Please tell me one,how can an employee treat me as such based on an assumption and how does a gift card go through of its not accepted? I'm disgusted and appalled by such an employee ,never have I ever been spoken to like that and rest assured I will never visit this spar again