You can resolve the issue by forcing recharge or renewing your billing information with the steps below:
1. Log in with your e-mail address and password from the Account page.
2. Click on a green button to force recharge, or you can select  on the upper right side to use a different credit card.
*When you complete it, 1,026 yen (tax-included) charges will incur.
*If you are using Docomo Payment, it will take 2-3 days to process the command.