One order and two lots of payments due to system glitch and no refund

I placed an order on the Mr D app with KFC Westville and when I was trying to checkout there was a pop up on the app to say that my order could not be confirmed at this time. I then went out of the app and placed the order again whereby it checked out as normal. I then received 2 deliveries from KFC of exactly the same order about 5 minutes apart. I advised the driver that something was wrong as I only placed the order once. He then informed me that he could not return the food and that I needed to contact Mr D. I then logged a query on the app and have since been advised that due to the fact I accepted the second delivery and that next time I must call Mr D immediately they are unable to refund me. Firstly - there is no notifications on the app regarding procedures to follow in the event of an error, secondly I was unfortunately busy in a meeting at the time of the delivery and was unable to make a call and thirdly, this was NOT MY error. How can one be expected to merely just pay their over inflated food prices for 2 deliveries which you did not order. This is absolute theft. I have even asked them to collect the food from me and was told they are 'unable to assign a driver'.