Have you tried using the "Restore purchases" button in game?

If you go into Settings > Tap "Restore Purchases" it should start some sort of animation and then confirm or fail (If the screen jumps back to the top, just scroll and tap it again).

If that doesn't work please contact us with a copy of your receipts and we'll manually restore that for you.

Here's how to get them:

ON ANDROID:

Just forward through either the Purchase Order Numbers in your receipts (the order number usually start with "GPA") or you can take a screenshot of the transaction in the purchase list in the Google Play store.

ON iOS:

Just send through screenshots of your Purchase Receipts from your Apple iTunes Store Account.