You can add extra credit to your account by logging into your Dashboard > Voice > Call Credit.  Once on this page, simply select the amount you wish to add and then press the "Add Credit" button.  On this page, you can also set your call credit to top up automatically or set up notifications for whenever it falls below a given amount.
Your current credit is displayed at the top left of any dashboard page.
If you need any further help today, please don't hesitate to contact our friendly support team on 917 900 1929 or by email!