1) If you have online applications on your device, remember that data usage
occurs throughout the day; hence usage will be billed accordingly.
2) Smart devices have a tendency to continuously access data network and
automatically download some updates for certain applications like Weather,
Stock/News alerts, social networking sites (Twitter, Facebook) and emails.
Hence it is recommended, you disable data from your handset itself to avoid
unnecessary charges by Switching off the settings.
3) Or alternatively check your handset menu to switch off data settings or auto
updates It is advisable to log-out properly before terminating a surfing
session thus ensuring unnecessary data transfer is avoided.