The best thing to do and the only way to secure your account is to transfer the characters to another account that you have the e-mail on, considering you have all the information this won't be a problem. Maybe monitoring him for a few days or finding out his location will help, try to do it late at night so he won't be able to stop the transfer via e-mail.
Once you transfer the characters ban the original account using a program and profit.
For more information read my new guide, it's long but has a lot of information on keeping an account: http://www.mmowned.com/forums/wow-sc...-accounts.html