Customer services need to fix it for you, but in the meantime, you can reset your phones data counter each month to keep a track on your data, or download an app such as 3g Watchdog etc.
I have no affiliation whatsoever with O2 or any subsidiary companies. Comments posted are entirely of my own opinion. This is not Customer Service so we are unable to help with account specific issues.
Please select the post that helped you best and mark as the solution. This helps other members in resolving their issues faster. Thank you.
