Can you elaborate what you mean when you say have it but you can't use it?
I received the Warthog code in Xbox email weeks ago and redeemed it, but I have no Warthog in the game, nor does anything Warthog related show up under Forza Horizon 3's Manage Game screen.
Now I did play the demo, which I later deleted to make space for the full game preload. Maybe the license was attached to the demo as some here have suggested? I don't really know.
I ask because while your news of people getting codes is good to hear, there seem to be plenty of us in this thread who have gotten codes and yet still don't have a Warthog.
We've basically got the full list of eligible people for the warthog, then narrowed it to those who have played and haven't had a warthog in their garage ever. You should be fine.
Ah, so its on track for a fix? Great news
And once these issues are behind you guys, take a well needed vacation. This game is fucking fantastic on every level. Kudos to those who toiled to make it happen.