That sux for me I guess...just got a new 8100 a month ago.
Did your 30 days run out? If not, return the 8100 and use a cheap phone for the remaining 8 days and then purchase the 8120 when it comes out on the 14th.
also you can update your contract at any time with Tmo and they give you a % off the full price of the device. now since you would have your phone for 2 months, it will only be a few dollars, but still something is better than nothing