I purchased the Hearts of Iron 3 Collection yet only received the base game.

[Obelesque]

I entered the product key in on steam for the collection and only got the base game. I do not know how to fix it and it doesn't help that I am locked out of the "support" page for the game.

Proof of my purchase:

 

[cmgreven]

Go to your steam library, find HoI3 and Right click on it. Select View Downloadable content. Any DLC's you own for HoI3 should be visible here.

 

[AndrewT]

If you are on a Mac, this is as designed - Steam only sell the HO3 base game on Mac, all the DLCs they sell are Windows only.

If that's the case, your best action is to get a refund from Steam, and buy the whole thing from GamersGate or direct from Virtual Programming instead.