I received a text message from Verizon yesterday telling me I’d used 50% of my data limit and that my billing cycle ends July 17. Today I get a text telling me I’ve used 75%  WTF?? I went into my app settings and made sure everything was set to download only when I’m on wi-fi, and it was.  ALSO:  Tap the symbol to the left of the home button, it says, “active apps” and there is an option to “close all” or just an “X” on some other phones.  I also did this  –>  When data usage is through the roof, the problem is that apps are using data downloads instead of Wi-Fi.
Go to Settings
Click on Data usage
Scroll down to where there is a list of applications. They are listed with the highest data user first. Facebook was on top for me.
Click on an application that is using a lot of data.
Scroll to Restrict background data and click on it. This instructs phone to download only via Wi-Fi.
Just above this it says “view app settings”. Click on this and click on Auto-update apps. Select Auto-update apps over Wi-Fi only.
Remember to turn Wi-Fi on.

I was reminded by a friend that I took many pics and videos Sunday and uploaded them while I was not on wi-fi. I most importantly learned I’d somehow turned my wi-fi off.  The good news is: with Verizon, if I go over data, it’s just $10 per gig.