Completely agree with you, bladddddd.
There really should be a toggle in the cellular menu to switch between LTE, 3G & 2G. Carriers in some parts of the world may well be switching off the 2G service, but that doesn't apply to everyone & certainly not where I am in the UK.
I spoke to AppleCare about my problem last month, but they were unfortunately quite hopeless, not knowing that the easiest way for me to recover my original carrier settings in iOS 6.0.2, would have been for me to carry out a full reset & restore from a backup. :(
I did too pass on my annoyance with the inability to switch back to 2G, should I want to, after an over-the-air carrier settings update has taken place & has subsequently replaced the 3G toggle with the LTE toggle.
I have also completed the feedback form some weeks ago. I hope others having this same issue will do this too:
http://www.apple.com/feedback/iphone.html
Hopefully, Apple may bother to actually take some notice of this problem, which will now affect a lot of iPhone 5 users.
The next iOS update will hopefully include the ability to override a carrier settings update & falling back to a 2G signal, should users want to, or need to, particularly in order to reduce the strain on the battery.
Until such an update is released, I'm sticking to iOS 6.0.2 :(