Refund my R149- I have the proof that you took it

I used my app on the 27 October buying food for my kids. The app took money from my FNB account but no delivery was done. I called Mr delivery to tell but instead of checking I was told that they never received the money. But my bank statement and my FNB APP is showing that Mr delivery took the money. Please refund my R149. I had to re-order and pay buy cash. What I don't understand why it didn't work when I was using my card but be able to deduct the money and when I do cash order the app start working. Please refund my money

I even asked FNB to help reverse the funds but still waiting.