Who I have the same questioned this topic

Why is it that i'm still accruing data charges while connected to my WiFi at home!  Does it pick the network over WiFi whenever it feels like it?  I'm being charged for data at 5:00 in the morning while i'm HOME sleeping.  I don't see any data charges for while i'm actually out in the afternoons using the phone....it's so weird!  Am i reading the DATA USAGE breakdown incorrectly?  I don't want a total....I want to see every minute that i'm using it that its charging me! 

How do you check on an iPhone 4 which apps are using the data and how much?  This would be very helpful!!!