If there was an issue buying coins from the in-app purchase menu and your coins aren’t showing up in the game, you can try checking your internet connection. You can also try restarting your device and entering the game again to check whether your coins appeared.  
 
If that doesn’t help either, be sure to contact our customer support and we’ll look into your issue. When messaging support, please provide a screenshot of your receipt or a screenshot of your purchase history from the App Store.