CRAP, CRAP, CRAP - that would be my feedback to them.
I had to wait for 30 or so minutes and I thought I was read to kill by the time 20 mins passed. I was very nervous and hate to wait in moments like GMAT, dentistry, or capital punishment, all having about equal impact on my distressed mind.

Yeah, if ETS can't help, can't they at least not stand in the way?
Did you try to complain with the GMAC?
At least if they don't cancel your scores, you may get your money back.
Of course this will probably take time and will remind more of the unpleasant experience....
The thing with ETS is that they are a monopoly, so even if they screw up a whole lot, GMAC will not drop them, for they will not have much choice otherwise. But, actually, GMAC said they were pretty happy with the services ETS provides. (I had a phone conversation with one of the representatives).