Uber cash scam?? 😡😡

I had $20 in Uber cash and I decided to use it on my Wingstop order + a 40% off promo I had. I go to checkout with apple pay and see they’re trying to charge me $21 when I only expected the 0.28 + tip. I saw another post someone posted on here earlier going through the same thing and someone suggested paying with my debit card instead of apple pay so I did but it still charged me the same amount. How do I get a refund??