Trainlink is updating its booking site and maybe other stuff I don't know.
Anyway, I have a 6 month Discovery Pass that expires today I think. Despite the booking page not having 3 month or 6 month Discovery passes for sale I was able to use my current pass to book a return trip. The only differences are that the name of the concession (they call a pass a concession) is different (180 day premium pass etc) and there is an extra $5 charge for each trip. Apparently the 3 and 6 month passes will be available only by Thursday if you want to renew (buy) a pass. Maybe.