I was able to get a netdirect rate refunded once because when making the reservation the date accidently got changed to the day I was making the reservation instead of the date I wanted three weeks later. I wound up calling the hotel directly and it was credited. I think calling immediately and the fact that I had re-made the reservation for the correct date helped.
But I also know that they can be quite rigid on the 'once this reservation has been made there are no refunds' language you see on the website.