Wrong order and sick attitude from staff!

I have had sent my younger brother to buy triple decker chicken and mushroom pizza which was not even part of their menu, he placed his order and they confirmed the toppings with him which was extra cheese and pineapple. Because we were all in a hurry, he didn't check his order up until we have left, we took back the pizza after some few minutes and the cashier said she didn't hear the triple decker part. The manager was also there and decided to protect the cashier, my brother explained that the only confirming part the cashier hear was extra cheese and pineapple not large pizza they have given him. The manager said she wont take the order back coz her cashier didn't hear that we wanted a triple decker, all that explanation came in yelling and attitude.

Fix this, perhaps the staff should be trained on how to listen carefully?

I called their customer service which the lady tried to intervene but the manager gave her version of the story which was untrue and she also dicided to cut my call off when I was still expressing myself about the order. I never had any issues with gauteng Debonairs before, but the one in Giyani plaza ruined my entire week!