I had followed everything you said, had all the details ready, but my goodness were they reluctant to give me my code.
They had me on hold, put me on to several different customer care workers asking the same questions and me waiting longer and longer.
Eventually I got through to a guy saying I had to wait around three weeks for the code and when I asked why he couldnt really give me a straight answer, and he quickly said goodbye and hung up.
I rang up again two weeks later (yup two weeks), and went through the entire process again, this time however I was more stern and said I didnt want to be put on hold until I was ensured a code.
That did it, and they gave the code.

Overall. the process wasn't very pleasant, but if you follow the tips here and have all your info ready then they can't really waste as much time as they want to. Be stern, I mean you want to get your phone unlocked to get on 48 right? 😉