Transmission software HELP

[toohotdoc]

Well i been having a problem with my Transmission but nothing major where it wont drive. The only problem is that the X5 seems to lag when i push the accelerator down at once and there is a short pause followed by a jerk. Before it would Jerk and take off but now there seems to be a lag, and this is not only off the start, even on go the X will lag. The Gear changes are still smooth tho, its just the pedal response. So i taken into the dealer, and i have extended warranty, they tell me first everything is fine and i was like "no its not" so then they call back the next day and tell me they still not sure but i can change the transmission software and it "might" repair it. So i was "okay" and then they want me to pay $120 for the software. So they are not covering it by warranty and at the end they said there is no other choice, What Ya'll think i should do? i;m confused especially about repairing a software that might not even be the problem. ahh, the stealers always seem to be playing with my wallet one way or the other but do i really need this software for my problem? or has someone else had the same problem with thier tranny?