+1
In addition, search the BB forums (crackberry etc.). I'm sure others have run into the same problem as you.
(Another idea, maybe more farfetched and as a last resort if all else fails, is to sign up for new service with sprint and cancel within 30 days. Swap the phone in between. (I would't usually condone this because of ethical reasons, but in this case, I think Sprint is being unethical with you. Just my 2 cents))