Ok, I figured out a walk around. IF you know someone who has the DLC working, copy the file from their 360 to a flash drive, and then to your 360. After that, you will simply go to the main screen, and act like you want to download it again. It will go from 1% to 99% and then say "Download Complete". When you go back to the game it will optimize HD content for the map pack and presto, it's installed.
Luckily, I had my wife's xbox to do this on, and it DID work. I never received a call back from microsoft, so I just had to figure it out. That being said, this was the only way I've figured out to solve the issue (even after 2.5 hours on the phone with the microsoft support people). I think it's absurd to have to do it this way, but... it is what it is, at least I figured out a way. Those of you who don't know anyone, who has it, use your account on someone else's xbox to download it...
