This happened to me a few weeks ago...HDNET was fine for months, then off the air. When I called DTV, they said I wasn't signed up for HD (free), once he changed it in the system, HDNET came back on. He was confused as to why I was getting it before being "signed up" for HD. Me too.
As for the comment of "some CSR's are morons", I think you're being nice with the term "some". I won't go into the details here of the 45 minute phone call it took me to get them to send me the Sat C upgrade kit.