I would be extremely pissed too! I used a family members upgrade, so I have to go into at&t tomorrow to get everything switched. I hope nothing gets screwed up either. Maybe i'll ask about what that means as far as seeing some people's grandfathered unlimited being expired...maybe they might know? Hope you find out!
Technically you can call with the IMEI number before you turn on the phone and do an upgrade swap (option #2 when you call 611). I went ahead and picked up a different sim from the store today that is hopefully correctly associated with my account. Not sure if the store or the phone will be more painful...
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Also, from what I hear Verizon just said "No subsidized phone for you loser unlimited plan peeps" so it could be worse. I used to have unlimited but just said whatever when tethering came out since I don't use that much anyway.
My brother on the other hand..... (it helps that I have home internet and he doesn't, but hey)