Hey Xavier, which trip was cancelled?? Were you booked on a short trip on their 51ft Riviera?
As mentioned recently in another part of the forum, Blackout charters in Cairns has a good reputation for day trips and being able to find sportfish including GT....there is lots of awesome fishing in north qld, it depends what kind of fishing you want to do....if you want to popper fish it will limit your choice of operators more as not a lot of them are experienced in that sort of thing...apart from Blackout which is in Cairns, not the areas you mention (Cairns is about an hour drive south of Port Douglas, and quite a way north of Airlie Beach), I don't know of any in that region who do that sort of fishing....hopefully someone else on the forum, maybe someone who lives up there, might be able to help out
Cardwell is halfway between Townsville and Cairns (about 1 1/2 - 2 hours south of Cairns) and near the hinchinbrook channel which offers good fishing inshore, plus offshore options...again though I can't recommend any particular operators
Hope you have some luck replacing your fishing time