You know, if it was me, I'd call the SEC hotline first and describe what's going on, and ask what my rights are. Then I'd call TIAA and mention I'd already been in contact with the SEC, who told me XYZ, and that I'd prefer to not have to file a formal complaint but will do so if my questions are not answered - immediately.
But that's just me. I like to know all my options so I'm negotiating from a point of strength.
Best of luck with them. If I can make any calls and/or get any info on processes for you I do have (supposedly) a dedicated TIAA rep through my old place of employment and I'm happy to phone her and ask for you.