You have to call.
For those that keep being told no fireworks, I would hang up and try again. My lady (Dottie) said they weren't booking for reservations after May 31. I said, "Oh I noticed that the WDW website had changed it's fireworks for summer and thought MAYBE it was in the system." She did a little digging and found it! I would keep trying until you get a CM that knows about it if you really want it.
HTH!
~nicole