I was pissed when I bought Black Ops 1 Hardened Edition and the area where the codes were supposed to be were blank lol! I contacted Activision customer support and everything went smoothly. I guess that they're not helping you because many others are having the same problem; so they're pretty busy at the moment. So, why can't you redeem your code?
I apologize for my language, heres what i've done so far: Tweeted activision support 3 days ago, still no responce. Went to my local GAME store (I live in sweden) they told me to call activison, i called them they sent me to their support site and told me to click on "I didn't recieve my nuketown 2025 code" eventough i recieved it, and it's not just 2025 it's zombies and the two themes. I still sent my request for a new code tough. I hope i get my hardened code and not just 2025. I also called sony they also sent me to activison support page.
I'm pretty sure that the 2xp is open to everyone that is currently playing the game. With or w/o the codes. Remember, you are not going to see the value of your kills double on the screen when they happen. They are POINTS, not xp. The points are used for your POINT STREAKS. Look at the after action report screens, I think you will see you are getting 2xp.