This issue is getting more common. I also recently had the problem where I lost DLC authorizations and the game advisors weren't helpful.
I opened a ticket on http://help.ea.com/contact-us and selected the e-mail option. I had to do this on the Dutch site, because that option wasn't available on the English one. I then tweeted my problem to http://twitter.com/askeasupport , along with the ticket number, and got a reply during the weekend saying the problem was solved. (This was an English reply to the Dutch support ticket. If you're very frustrated, just type an English message on the Dutch support site and then let the Twitter guys look into it.)
So in short, EA can manually link the DLC back to your account, but some of the rookie game advisors simply don't know enough about the issue to assist you. Some of the people I chatted with barely spoke English.
