******* ASAP app

I received a voucher from work to use at Pick n Pay. It was specifically for their delivery app. I ordered some items from the app, or tried to, and it informed me that I needed more than R0.00 to place an order after already spending approximately R400 excl delivery. I then add some things to my cart and it tells me to qualify for delivery I need to have a cart value exceeding R100 (this after spending nearly R500 excl delivery and applying the voucher) anyway, I add more things to my cart and eventually it's satisfied enough for me to proceed. While processing the transaction, the app has an error and it doesn't go through. I go ahead and try again but this time, my voucher is saying it's already been used. I emailed Pick n Pay 48 hours ago with no response thus far. How can it take 48 hours to resolve a simple query like this. This is ridiculous. I will NEVER be using this app again.