Alienware Corporation Rebate Ripoff voided my $500 rebate Miami Florida

I purchased an Alienware computer for my son for Christmas with an understanding that I would receive a $500 rebate. After waiting 6-8 weeks I finally called to see where the rebate was and then they tell me it was "voided".

Several time I have contacted them and each time it's a different story:
The rebate was not received within 45 days
The original invoice was not received with the rebate
A copy of the invoice was not received with the rebate
Your rebate is approved, but when I called back to get it in writing, they said that nothing but the rebate was received.

This is all a bunch of lies. I did include a copy of the invoice and I did send it within 45 days. Why would they deny my money?

Craig
Houston, Texas
U.S.A.