I would definately call and ask them about it...maybe they can give you some sort of refund or credit your credit card for the difference. Good luck and let us know how it goes.
No one is really sure how Disney decides who is getting one. Some things that may help: go to the reservations website and play with some numbers. Try the prices for one or two luxury resorts, then one or two moderates. And order the trip planning video.
Either of those things may be what got my name on the list, we're not sure.
And, regardless of what else you do, join AAA. Their discounts range from 10-20%.