I've had this problem too many times. If I log onto O2 from my laptop I can view my bill, any charges etc.
However every time I use my iphone to log into the site using my username etc. all I get is an overview so I cannot see the breakdown of charges or anything so I have no clue what charges I've gotten on my bill unless I use my laptop
Anyone got a solution to this problem? Been having it for months now and it's getting a bit beyond a joke