just call customer service, and say when the automated machine comes on to direct your call, say "cancel". You'll get transferred to customer loyalty, and from there you just need to threaten to leave, or something along those lines. What i did was tell them I had high hopes of switching T-mobile to get the Evo (which I did in a sense.), and the rep told me he would give me the g2 for full upgrade cost.
Came out to 230, just need to do the mail in rebate.
*also, mention how you've been with Tmo for years. I mentioned Ive been with the company for 6 years, and they really hooked me up. I love tmobile!*