Sorry I was playing when I posted that...here it is step by step.
1. Access the email account that you used to register your XBL handle.
2. Find the Specialization email that they sent out which helps unlock the rest of the specializations beyond the two that the game started with.
3. Download (or if you have already downloaded it, redownload it via Account Management).
4. IMPORTANT - Access the XBox Live Marketplace via the Halo 4 MAIN MENU. NOT by the XBL marketplace on the dashboard. That way it won't work. You have to access it via the XBL option at the H4 Main menu.
5. Crimson map pack should appear with a "*" right beside it. Click it and then click download below it...download should start (size is around 550 mb). No credit amount should appear beside it, it should say 0G
From what I'm reading online there's no way they can ban you for it...it's a **** up on their part and they pay the price of it. I heard that for the other people that have already bought it or paid the seasons pass for the maps they will be releasing a fourth map pack in the future.
I honestly have no sympathy for XBL/343. To release a new map pack so soon after the release date of the game? Kiss my ass I paid full price for this game when it came out in my eyes this map pack should have been included. Basically what happened was they didn't realize that the Specialization code they sent out also included the download for the Crimson Map Pack...so they really screwed up.