Still Having issues with Specialization Code

I purchased my CE on launch day, entered all of my codes. On the 17th of DEC while I was out of town for awhile I got an msg from live that my code had not been used, the msg said it would expire in nine days. I did not get back till recently and was told that I could choose my specializations after 50 by a friend. I had picked wetwork for the first one, and when I went to choose the second I was only offered operator as a choice. I was told that my code had not been used and I would be able to pick anyone after completing the 10 customary levels in my current which is 67 operator.
I want to know is the code for being able to choose a specialization at each 10 levels of acheivement, or just to unlock to make them available as you climb and they are picked in succession automatically? I can see all of the specializations, I want to know if I should be able to choose and not have them chosen for me at every 10.