If you successfully made a purchase through the App Store and your coins were not added to your balance, something you could try which usually works is to completely close out the app and then reload it.
Sometimes it can take a bit longer for the iTunes servers to sync up with our own, and this restarting of the app a couple of times can jump start that process.
 
If you have tried this and your coins are still not reflected in your balance, please contact us so we can manually add your purchased items.
It will also be greatly appreciated if you could provide the screenshot of the purchase receipt from Apple with the following information to help us check for you faster.
  1. Order date
  2. Order ID
  3. Document No.
  4. Item name
  5. Item price
  6. Type of currency (HKD/USD/EUR...)
(Apple will send the receipt to your Email after you successfully make the purchase.)