At&t Iphone 5s data usage problem?

My iphone 5s is always connected to my home's Wi-Fi, but within 3 days of my new billing cycle I get a text saying I used up 90% of my data. I haven't left my house in those 3 days, besides going food shopping and going to the bank. What can I do to fix this problem?

At the top if will say Wi-Fi, LTE, 3G etc… It tells you what your current connection is.

  • Under settings on my iPhone, does the data usage include Wi-Fi usage? Because its stating a ridiculous amount and I've had my data off… And my Wi-Fi on. Does the total of data include the amount of Internet I'm using when on Wi-Fi? I'm so confused
  • Memory Usage Problem With iPhone? I have a tethered jailbroken iPhone 4(GSM 2012), i only have 3 apps from the app store downloaded, and a few more from cydia, yet my iphone says i've used up around 6.1gb out of the 8gb i have, i can't download any apps cause of this, yet i also don't know what's taking up the space, is it the cydia sources?
  • IPhone: settings cell usage vs AT&T's data usage number? AT&T has a number, by calling it will send you a text message telling you how much usage you have used on your data. But also in the iPhone there's a cellular usage count in the settings app which also tells how much data you have used. Both of my cellular usage counts are different. Which is right?
  • IPhone 5s AT&T Data Usage Problem? I bought my iPhone 5s about 2 months ago. Since I had it, my data has spiked up so much. I was on the 2 Gb of data plan for AT&T until I got my iPhone and they switched me to the family plan. When I had my 2GB plan, I almost never went over with my Galaxy S3. Now with the iPhone, I used 13.6 GB! My bill is now up to an extra $200! What do I do about this? PS: Last month I used 7 GB