App doesnt work for my iPhone

I was trying to buy some credits because I got a gift card and wanted to buy 60,000 dollars which is $2.99 in this game. Now the app does not work. I have deleted it and re-downloaded it and it still does not seem to work. I have this app 4 stars because it is a great app and its a fun game but I cant play it if it doesnt work. Whenever I try to go into the app it shows me two screens and the one that says loading then just blacks out and exits the app. I know I have enough storage because I have 64 gigs and have deleted many app recently. Please developers try to see what is wrong and how to fix this.

dannydoood about Mini Motor Racing