Did you follow-up?
I didn't even have to call. Just an email and the guy processed the rebate and I got the check a few weeks after.
There may be some truth to the AMPs not being able to run the factory OCs though.
I had to back mine down to reference clocks...but it's enough that I'm not comfortable reselling my 580 to someone else. It works just fine at 759, but yeah...probably will go back to eVGA myself once I upgrade.
And yeah - I'll have a 580 as a "back-up" test card in my box of test hardware. Pretty funny/sad at the same time.