i would call back and just be polite and mention youve been with att for a while and you are really interested in trying a new phone... you just need an agent in a more "giving" mood...
ive had 2 separate ladies and they were both "happy" to "give" me the upgrade if that makes sense lol.... that and as soon as one mentions they can upgrade you, make sure they put that in your account notes... thats what i did... so the next agent can help you once the phone is released since they cannot do the preorder via phone.... also, stores will give you run arounds and waste your time as you wait and wait and wait there inside for them to tell you ya, i can do a partial early upgrade, uh no thanks, good bye....
good luck! saturday is almost here!