I believe they might have access to the internet from their computers and could see the listings that way. I also called once on a game I should have received but did not, while also voicing my displeasure that they advertised I would get Giants games in HD and hadn't seen a single one yet... He assured me that I would get GIants games in HD, just not THIS game, and proceeded to log onto the D* website and look through the TV listings for the next week or so... At which point he said "I don't see any Giants games in HD in the next 2 weeks, but I'm sure you'll get some!"
I don't know if you already know this, but the FSNBA HD feed is only available in a narrow area that is covered by the SPOT beam, which is basically downtown San Francisco. D* won't tell you this. I called as soon as I got the HR20 in October, since I was eagerly awaiting seeing the Isles v. Sharks in HD. Of course, I never saw Ch 96. D* told me the usual "not all games are in HD.." crap. It wasn't until I contacted FSNBA directly that they told me about the limited area. (I'm in Nevada).
The CSR's are completely useless. Next time you have a question, consult a Magic 8 Ball.