POOR POOR SERVICE WITH NO KNOWLEDGE

So i placed an order online with Debonairs norwood i spoke to the lady by the name of Andile which i was asking about using the vouvher i received for my birth she kept on saying online so i asked which online app or online like going into the internet the lady was clueless so i placed an ordered and wasn't able to put in the voucher number so she had to cancel the order so i placed another order but made a mistake so they have cancelled 2 orders numbers now so i spoke to the manager or whoever who was it he told me that they cant cancel my order and i didn't wanna cancel i just wanted to make a correction on my order this is just poor service the guy was even rude telling me then its okay if i want to cancel and i should not ever place an order with them am really disappointing in the service that i received imagine a supervisor telling a customer not to ever place an order with them am shocked by the service that i received am a customer and am paying am allowed to make mistake or make a correction on my order this is so highly unacceptable and worse to be rude to a customer he was very rude and the people at the shops must be trained on the app and the online so when we call they can be able to navigate with you