Originally Posted by
luv2vacay
So the First cabin is currently "no available".
Are you actually seeing a seat map, and is that showing every seat as unavailable? If there is no seat map and you just have a red message of some kind, then off the top of my head I'm not sure that you can set an alert anyway.
The other to check, if you're not seeing a seat map of any kind for that cabin, is whether that flight is actually planned to operate with a first class cabin.