On my 3rd iPhone 5 with LTE, my battery lasts 4 hours tops, again. Any ideas?!

So I'm on my 3rd iPhone 5 within three weeks. The first one was fine, using LTE, no battery problems, then I upgraded to 6.0.2, and then bam, 3 hours it would last. I was then aware there was an issue with the software upgrade. I exchanged my phone twice after that and both of them have been lasting 4 hours tops without the upgrade, so it was still on 6.0.1. I'm getting absolutely sick of this, its eating itself alive. I work in telecommunications so I'm aware about turning things off like bluetooth and wifi when I'm not using it, but I cannot fathom what it could be! It's beyond a joke. Any ideas?

Jake Pennington

iPhone 5 16GB Black - EE UK - LTE