iPhone balance notifications are probably the only downside to having an iPhone on Pay As You Go, every time you send a 
message, make a phone call or use data without having a data package in place, you will have to dismiss your balance every time. It may be nice to sometimes see your balance, but if you send a lot of SMS messages like me then it soon gets frustrating.
I decided to research the subject a few months ago to see if there was any way of removing it, a few threads on some forums but no conclusive answer. I got in touch with O2 to get it removed but back then they told me that you couldn’t remove it. There was nothing in Cydia to get rid of it either. But yesterday I got in touch with O2 again, after reading that the carrier can turn it off at their end and I woke up this morning without having to see the balance notification screen. So to remove the balance screen just get in touch with your carrier, whether it be O2 or any other carrier worldwide and they should be able to disable it for you. I hope this has helped and leave your success stories in the comments.
Sam's Blog 