I can hardly believe this issue has been marked "Closed" at that GeekBoy's post is labelled a "Solution". It's anything but, it's just a list of unhelpful excuses.
My son has had an iPhone 5 for a year now, and until this month it chugged along using an acceptable amount of data. This month, I bought an iPhone 5c for another son, adding a fifth line to our four line share plan. Previously we were always edging our 10G data plan limit and quite often going over (I use my BlackBerry Z10 - *awesome, underrated, problem-free phone* - everyday at work as a mobile hotspot, so I expect high data use). To support the new line, I upped our data plan to 20G just to be sure.
Then my first son's iPhone 5 went crazy. It was downloading 500MB per day all of a sudden, unbeknownst to anyone until shocking notifications came in that we're 75% into our data plan way, way ahead of expectations. This is quite unexpected since it's summer, he's out of school, and he's always home. He's the teenager you can't get to come out of his room! So our home WiFi is always available, and we made sure his phone was on that network. The phone says it is, but it seems to never use it.
We couldn't figure out what app (if any, could be a carrier update or an iOS update) was the culprit, so we took the phone into the Apple Store where they wiped it, reinstalled the OS, and we set it up with a fresh iTunes account. No dice. Last night it downloaded 500MB again.
I've found that Apple points the finger at AT&T on this one, and AT&T points the finger back at Apple. The recommended solution from both parties is this, "Time to upgrade that phone!" which is a non-solution.
By the way, this is the second time we've dealt with this problem. My wife's old iPhone 4 never, ever used a WiFi network as far as we could tell. Never once, despite multiple trips to the Apple Store and to AT&T. Her data use wasn't too bad however, so we just lived with it for two years until she became eligible for the iPhone 5s upgrade.
But seriously, half a gig per day? And both Apple and AT&T are unconcerned about understanding why? Offering only perfunctory customer support and making down issues as "Closed" and "Solved"?
Well whatever. But tonight I'm sure my son's phone will eat up another 500MB.