Dangling of empty promises

So I got a voucher from Debonairs for R50 to redeem when I purchase using the app. I took my time to download the app to redeem it. But while placing the order the voucher showed me that its redeeming only when I finish payment the amount is not discounted. I call the call center they tell me only the store I ordered from will assist me. I try calling the app which took me 20min to go thru even when the call is ringing with no answer. When answered I was placed on hold for 5min. When I finally got someone to enquire to I was told they can't do anything about it and I must just take the order already on the way. An order that then took an hour to come through. I pizza was dry and no toppings to make it worse. I haven't had such terrible service from you guys. Please stop dangling carrots in front of a donkey only not to give it. Stop false advertising. 507135 that's my order number. Please fix it.