If you successfully made a purchase through the Google Play store and have received the order invoice from the Google Play Store, and your purchased items were not displayed, something you could try which usually works is to completely close the app and then restart it.
 
Sometimes it can take a bit longer for the Google's servers to sync up with our own, and this restarting of the app a couple of times can jumpstart that process.
 
If you have tried this and your coins are still not reflected in your balance, please contact us for help.
 
It will also be greatly appreciated if you could provide the screenshot of the Google Play Store purchase receipt with the following information to help us check for you faster:
  1. Order date
  2. Order number (starting with GPA)
  3. Item name
  4. Item price
  5. Type of currency (HK$/USD/AUD etc.)
(Google Play Store will send the receipt to your Email after you successfully make the purchase.)