Hey, I just had this same problem. I ended up contacting customer support on the activision website via their chat function. They needed to verify my email address, login, and gamertag for my elite account and my xbox live account. After that was done, they checked and saw that I was owed the double xp and credited it to my account. I then logged into mw3 and went to the barracks....here it took about 30 seconds or so, but it finally showed up with my double xp for 2 hours. The whole process took about 10 minutes and the customer support was fantastic!