Customer Service/Theft Steers Wonderpark

I went to steers in wonderpark after ordering on the steers app. I approached the cashier by the name of Dineo .At first she disputed my order was appearing on the screen and when I corrected her she found my order. This is after going back and forth showing her the order on my phone and her insisting that the order which i have already paid is not appearing. I am assuming they sell orders that customers have already paid because she was insisting there is nothing she can do because that order number was not valid. After the incident and she requests the milkshake from someone she then says I need to present my slip on the order that she processed. She is very rude and ********* to declare my order not on the system for her to then go and sell it for money to the next person. The Supervisor so called because the guy was working in the kitchen and the Supervisor at that hour was out of the shop. She is really has a disgraceful attitude and will have steers loose customers. She backchats and invokes other customers to prove she has done nothing wrong.