So we scratched that and went through an excruciating online form and eventually sent the phone to some repair center in Texas, I think. After about a month the ticket was updated (but no alert email sent about it, the user just happened to check the website) saying that the phone's warranty was void and it could not be repaired (no further explanation).
After a couple of calls, I finally got someone to tell me it was void because the battery was replaced with a third party one (which was, admittedly, news to me). Then, similar to your issue, they shipped it back to the wrong address (leaving out the suite number) so it took another month just to get the phone back.
I was really stunned at how awful the process was overall, compared to driving ten minutes to an Apple store and usually just having an in-warranty phone with a legitimate issue swapped out on the spot.