Tink, I would not look into a 3rd party changing your battery until you've had Apple have a look at the phone. You saying it would be 14 months before you switched leads me to believe that you are on contract/still paying for the phone. If that's the case you should still have a couple months warranty on it. Even if you don't, once a third party does something to that phone Apple won't touch it with a ten foot pole.