Well, hopefully, someone else here can give you more up-to-date info, but I know you must be a little stressed, getting this close to your interview, soI'll take a shot at it.
Call Greta first thing in the morning, around 8:00 a.m. and if you don't get her, leave her a message that you still haven't received your interview packet, and at the very least, you would like to make sure that you have a confirmed seat from ______ city to Atlanta so that you can be here. It's no big deal, they'll just enter it into the rez computer, so when you show up at the ticket counter (or the gate, if you are badged for your departure airport) you'll just show ID and they'll give you your ticket. If you don't hear back from her by 4:20 or so, I would try her again. If she's not there, she might be out of town, so I would call Stephanie, and just tell her that you haven't been able to make contact with Greta and you are trying to nail down your travel plans so you can get here . . . . . . if that doesn't work, panic. Heh-heh . . . just kidding. If you can;t get it resolved by the end of the day Monday, PM me, and I'll see if I can get you the number of the appropriate person.