If you are having trouble purchasing gems or items, please try the steps below:
1. Add a new payment method
Go to "Google Play Store app" > tap "Menu" on the top left side > "Payment methods" > change to one of the payment methods listed > The new payment method will be added to your Google Account.
(Please note that Available payment methods may vary by location)
2. Update your payment information
Go to "Google Play Store app" > tap "Menu" on the top left side. > "Payment methods" > Update your payment information
3. If the Default payment method is declined;
Contact your bank/payment support center to make sure there isn't a problem with your payment account.
If you are still having trouble, please read the articles below that may help fix the payment issue :
(1) [Problems with in-app purchases]
(2) [Fix payment issues with your account]
(3) [Need help with the failed transaction?]