Apple's firmware updates won't re-apply on top of themselves, since it checks what firmware is on the drive to see if the update is necessary.
This might work: Follow the posts in this other thread in the MBP forum, where you'll find firmware to render the drives region-free.
http://forums.macnn.com/69/macbook-p...ware-c2d-mbps/
Now, obviously, there's some risk in updating to region-free, just as you found some risk in updating using Apple's firmware updaters. So, it's up to you whether you want to seek redress from Apple first, on the theory that their updaters borked the drive.
Anyway, if Apple doesn't help you, you can using the above-mentioned updaters, because you'll have nothing to lose.