Change of Order at the counter before Pizza was made

The service I received at Debonairs Protea Gardens shop no.77 It was BAD, The cashier’s name is Nqobile, I ordered an incorrect Pizza and I saw that it was incorrect when she was giving me a Receipt and I was still at the counter I asked her to change my order from 1 Large Crammed Crust to Cram-Decker and she told me that it is impossible to change I asked her that why because me Pizza was not made at the time, then I didn’t want to argue with her and I waited for the order and asked the guy who gave me the order that I wanted to change my order before the Pizza was made then this guy told me that it was possible to change but now as the pizza was made I can’t change anymore so I took the pizza and went home.