so i am eligible for a $150 upgrade from a nextel to a sprint phone. I was trying to get the LG lx 290 and when i tried to upgrade on line everything said it was free but then i clicked to the next page and it said 50 mail-in-rebate charge...y/? i thought it was free so why do i have to pay $50? i dont have money to send them and xtra 50..what can i do?