Have you tried them via phone at:

408-349-1572
OR
408-349-3300
OR
408-329-5151

Office Hours 8:30 a.m. to 5:00 p.m. PST

Email: [email]account-security-help@cc.yaho[/email]o-inc

With your Yahoo! Username as the Subject.
I am still waiting for a reply. I sent my email request last night around 4:30pm PST.