We can only accept purchases from the store you downloaded the game from (eg. iTunes or Google Play). If you have problem with their purchase flow, you can try contacting the support email.
1. Make sure you have the latest version of the Google Play app 2. Make sure your device time is correct. 3. Restart the device if both of above aren't working. 4. If still doesn't go through, please contact Google Play on why your card isn't working.