The phone started losing battery life a while ago, the battery would run flat within a day just on standby, and would also go from say 60% down to nothing quite suddenly. I've tried a third-party replacement battery and it's not much better. Has anyone had good experience with replacement parts? I'm not sure if it was just a poor quality battery that I tried, or whether there's something else wrong. Not my phone, but I'll be the one paying for a new one if I don't get it fixed, and I've just seen the price of the Iphone 7.