Battery/LTE on AT&T iPhone 5
So I've had my iPhone 5 on AT&T since release day, it's still running iOS 6.1.4, and I had the battery replaced by Apple about a month ago. Before I explain everything, the point here is I just wanted to see if anyone had suggestions as to what may be causing this so I know who to contact or what action to take, whether it be Apple, AT&T, or handle it myself.
In terms of battery, I normally get an average of 10 hours usage, 25 hours standby on my phone, but have seen the usage, under normal conditions, vary from 9-12 hours on a single charge. It's always been this way and I can usually use my phone normally for two days on one charge. For LTE, I usually have 2-3 bars around my house and at school, averaging around 10-15 Mbps, and hitting highs of 20-50 Mbps on a full 5 bars. For whatever reason, over the last week and a half, my LTE on 2-3 bars can't break .5-1 Mbps and even with a full 5 bars only hits around 6. However, this isn't 100% consistent, but it is consistently worse than it used to be. I'll get >1 Mbps 8/10 times, >6 the other 2, and have only hit ~45 Mbps a single time, but that was only in one location yards from a cell tower - and these are all measures of downlink but upload is bad as well. I've switched it over to HSPA+ and managed the totally normal 3 Mbps average. Now, using HSPA+ is horrifically bad, (it's the network technology and Qualcomm's baseband, not speed) but that is both an argument for another day and the trade off for being able to use my cellular data. Also, my battery has been dropping like a rock (on LTE now, battery always sucks massively on HSPA+). Today, for instance, I only managed 2.5 hours usage, 8 hours standby with 50% remaining. And this is always very light usage ranging from messages to music to Twitter. So that's the situation.
Now, I've been through the full suite of troubleshooting techniques over the last few days, including: hard reset, popped the SIM card, reset network settings, even restored the carrier file in iTunes. There haven't been any network changes lately, AT&T has finished their LTE deployment here and according to the field test app, I'm still on band 17, like always. It's a fresh battery and I couldn't fully determine if it's a potential hardware issue since it's been working absolutely fine for a year and a half. Nothing has changed with my usage habits and my friends' iPhone 5s (iOS 6 and 7) on AT&T haven't seen any change in network quality. Side note: If, on the off chance, it's a software issue, then I'm just screwed and I'll figure something out because I can't restore my phone, I'm not in a position to buy another one, and I'm sure as hell not updating it. But again, this shouldn't be an issue and it shouldn't be anything related to the hardware since it was working fine for all this time. Anybody got any ideas?