Currently Being ModeratedOct 3, 2012 6:22 AM (in response to Stupid Little Genius)
I have been experienced the same issue twice this year. The first time, I experienced such shocking service from my UK network provider, Orange, that I left the network. Not only wwere they unable to identify the issue (or provide any meaningful support) but I lost approximately £70 (about US$110) worth of credit from my account which they refused to refund.
I subsequently swapped to the Tesco network and experienced the same issue again (immediately after "upgrading" to iOS6). The support this time was far better (although they were unable to identify the cause of the data leakage but did agree to refund me the cost of the data that I had loast at that time (approcimately £30 or US$50).
Having undertaken a fair amount of research, I believe that this answer provided by Allan Sampson on the Apple Communities pages may be the solution - in my case, I have subscribed to iTunes Match and am reasonably sure now that this is the cause of the data leakage:
Turning 3G network access off alone does not turn cellular data access off completely. Doing so disables 3G network access only. When 3G network access is off, your iPhone will be connected to your carrier's EDGE or GPRS network, whichever is available at the time. If you have 3G network access enabled and you are not in a 3G network area, your iPhone will be connected to your carrier's EDGE or GPRS network, whichever is available.
To turn cellular data access off completely, turn Cellular Data off.
As already provided, when your iPhone is connected to an available wi-fi network, it will be connected to the internet via the wi-fi network while you are actively using your iPhone. When your iPhone has been asleep for a period of time while connected to an available wi-fi network, the iPhone will switch to the cellular network to save battery. If you have an email account or accounts set to be checked for new messages automatically, any new email will be downloaded via the cellular network and any Push notifications enabled will be downloaded via the cellular network.
To ensure there is no data access via the cellular network, turn Cellular Data off at Settings > General > Network."
Currently Being ModeratedNov 12, 2012 10:01 PM (in response to JPL1)
Iphone 3GS. updated to iOS 6.0.1 Friday. Data usage until then about 300MB
Sunday Morning around 4am. Phone incredibly hot even though connected to charger and home Wifi network. Usage exceeds 3GB for month and extra 3.5GB. Total usage in 12 hours 6.5GB.
Sunday afternoon after receiving message from AT&T about excess data, turned off Cellular Data and 3G and limited to only Wifi.
Monday evening 2GB cellular data. Total data usage in 2 days 9GB????? W/T/F ???
Even when 3G and cellular data is turned OFF, 2GB used up?
Now, turned OFF Cellular data and Wifi and using it as a regular phone with texting and calling. Maybe will buy a regular phone and be done with all these useless charges. Someone should be held accountable here.