How to get back to karkand dlc for bf3?

Okay so I pre ordered the game for xbox360 from GameStop then entered the online pass code and physical warfare code the first time I played and now it wants me to pay for the new dlc but I was told back to karkand should be free with any pre orders from GameStop
Was there a third code that was supposed to be with the game?


Answer:

If you load up the game you'll be asked to download the update, as long as you are eligible to get it. It's about a 2GB download so you'll now it's the maps.

If you preordered you should get them, ring up EA Customer Support if you can't find them and they'll give you a new code.