Is AT&T doubling the data that's ACTUALLY being used?

Okay so let me start by stating my current set up: iPhone 5s, AT&T, unlimited Text, Calls, 15gb month plan SHARED. Former setup: HTC Evo 4g, Virgin Mobile, Unlimited Data, Text, Calls.

My problem is this… My girlfriend, has the same phone as I do except she has one thing that I don't, Wi-Fi. She has it at home and at work so in reality, the 15gb data plan is pretty much all mine. The first month of AT&T service after switching from Virgin, we were on the 10gb data plan which we blew thru in about 8 days. Has to be some type of mistake right? Wrong. We were forced to switch to the 15gb plan. The usage was a few YouTube videos, Instagram, Spotify a few hours a day at the gym, a few game aps, eBay, Craigslist, the usual. Since then I have turned off everything including LTE (except for messages) deleted all apps and ONLY turn data back on things when I need them, use them for a sec then turn their data back off. We're now a week into the billing cycle and it looks like we're going to be close to going over. When I was on virgin mobile with unlimited data I was riding on 4g 24/7. I would have spotify on from the moment I woke up to the moment I got off work, I would watch continuous YouTube videos as well as play game aps. I would even watch netflix about 4 hours a night. I finished the entire series of DEXTER in ONE billing cycle. My data usage NEVER went passed 6gb of data and must I remind you I was never on Wi-Fi. Is AT&T Charging 3mb for every 1mb I ACTUALLY use?

Well, not really.

Netflix streaming takes 0.3-1.3GB per hour (depending on low or high quality)

And when streaming to a phone/tablet, it tends to be more towards the high quality.

So I don't see how what you say is possible. 4 hours a night would equate to 2-4GB of data a night.

Which would drain you in 3-4 days.

I've been with AT&T now for 4 years, and have never gone over. My brother and I are on a shared 10GB plan (used to be on a 2GB plan each), and we have been managing our data well (and we use YouTube and Netflix frequently).

If you don't have Wi-Fi, then streaming videos and such should not be something you do. Not on a data plan that doesn't have unlimited data.

What I noticed is att has tapped internet on to my bill! Why? First caught my attention when the phone they sold me stopped turning on and over heated! So I just pulled my battery out and sim card and waited a week with no phone for the new one. Anyways it was just starting a new bill cycle and it showed that 6 days on the bill I used 2.5 gbs. No calls or text just internet? Made me wonder I tested theory as my bill is now almost forced on 30gb. So this month alone with internet turned "off" and Wi-Fi "on" 100% certain that cellular data not turned on once says I myself uswd 3.5gb and my husband used 5.5! We're on Wi-Fi not cellular data. You call att they will resolve this by asking if you want to add a higher data package always not to look for a resolution. Maybe you should get Wi-Fi installed at home as it is 50 dollars tops which is one nights worth of att services