iphone 5c using excessive data

Good afternoon,

I am having an issue that seems to be known by quote a few. My wife had her iPhone 4S for over 4 years and 4 months ago decided it was time to upgrade. She decided on the 5c as we were able to get it for $0. Right from the first month she got it she has gone over her 1GB limit. On her 4S she never went over unless it was intentional. We called our carrier (koodo) and they were nice enough to wave to overage fee and gave us tips on how to stop it from happening. Well it has happened every month since then and I can't figure out why. I am an apple guy, my first computer was an apple 2, and my brother used to be an apple tech so I know my way around a MAC both inside and out.

So far I have done all the basic and obvious things listed online and given to me by our provider (turn off app data, check wifi, etc.) and while it has lowered the data usage she is still using about 20-40 megs a day even though background data is off for the data sucking apps and she is connected to Wifi. I am not at a loss for what to do short of turning off cell data entirely but that is not a fix in my opinion.

I have a samsung s4 and I use about 100 megs of data a month and my wife uses over 1.5 GB. I fly to different cities 4 times a month and my wife is at home on wifi. If I turn on Wifi on my phone then it will only use wifi, if the wifi looses internet then my page or video or whatever fails to load. I found out that apple does not have something like this, why not? Why is there not an option to turn on that will disallow auto use of cell data when wifi is lost or weak? I love apple and always have but I consider this a huge failing of the iphones.

So now onto the main point of this message. I have not seen any recent postings about this issue so has this issue been fixed and if so what is it? If it has not been fixed then I ask why not? I do not have the time to try and this and try that and maybe this will work or maybe this will. I work a lot, often times away from home and my wife is looking after 3 kids so she doesn't have time to mess around wife's 5c has been plagued with issues. Should I take it in to an apple store to be checked out? The thing is the closest apple store is 1.5 hours away so i don't want to waste a trip up if it wont help.

I love my macbook pro (using it to write this posting), love my power mac G4 (yes it's still working), and I love my iMac i5 but if the issues my wife has been having with her iPhone are indicative of the brand and have taken this long to fix, or have still gone unfixed then I will happily stay with my samsung and will be advising others to do the same.