I've been on the phone with Apple Support and online with their chat support since roughly 10AM (it's 3:30PM now).
After hours of arguing the point that it is undoubtedly the software update which has rendered my phone essentially useless (I rely on the phone for conference calls for work, and for listening to music throughout literally my entire day), they basically told me "Too bad" and instructed me to go to the store, to have them do what I already know they're going to do (and I've done on my own, i.e. hard reset the phone, factory reset, etc. etc.).
Apple is clearly covering up the fact that their updates are rendering older devices useless/unusable. I let them know the only acceptable resolution to this issue as far as I'm concerned would be to somehow upgrade me to either the 8 or the X, since this is only the most recent issue I've experienced since the latest iOS update, and all together, the issues are making the phone essentially a brick to me. They didn't care at all.
I can honestly say that I will never purchase an Apple phone again, and am extremely hesitant to ever purchase any Apple product again after this experience, because their "support" is useless, unemphatic, and keeps going back to the same "solution"; buy a new phone (the iPhone X and 8 both work great with their latest updates!).
Never again Apple, never again.