If you cannot purchase any gems, we recommend that you read these help articles:
1. https://support.google.com/googleplay/answer/1050566
2. https://support.google.com/googleplay/answer/1267137?co=GENIE.Platform%3DAndroid&hl=en
If this problem happens again, please go to the Friends tab and click on the Settings icon.
Then click on Help center and submit a request