Unlocking Specializations after November 20

I got Halo 4 on christmas and i have been playing since then i realized that all the specializations were locked. I looked up on online about how to unlock them and it said the code was given out November 20 at 11:59 PM EST.I then looked up if there was a way to get it after November 20 at 11:59 PM EST but i found nothing please help.