YOU CAN FIX THIS PROBLEM AS FOLLOWS.
Go to settings, click on > Privacy, > scroll to bottom of page, > System Services,
Turn all of these services off, especially the, Mobile Network Search.
Also turn all the other apps., location (GPS) services off.
The only one that I leave on is, Find My iPhone, as I need this one on of I lose my iPhone.
Note :- By turning off all of these you are stopping the iPhone sending your position to your network provider.
Especially the Mobile Network Search. This does not have anything to do with finding your mobile network.
What it actually does is send "your position" to your network constantly.
This uses a lot of battery power.
TRY IT.
You will still find your mobile network.
This should really be named "Mobile Tracking"
Because that's what it's doing, constantly tracking your every move, while you are within range of your network.
I NEVER TURN THIS ONE ON.
For all of the other apps, It is really very easy to turn them on, when you want to use them, As they always remind you That they are not turned on.
Also make sure that you close all webpages and or applications as follows,
While in your home screen, double press the home button, then everything that appears along the bottom of the iPhone home screen is open and remains open Until you actually close them.
You must close them by pressing and holding your finger on one of them, until they begin to shake, then you can close them by tapping the X on each one.
Also keep your screen brightness on auto, or manually, on a fairly low brightness that is suitable for you
THIS WILL ALSO SAVE BATTERY POWER