How do I go about recovering a stolen account?

My long time account was stolen this afternoon. They changed the security email, so whenever I try to reset the password it goes to their account rather than mine. Which - is kind of crap that they were able to change that without any notification on my actual email... but I digress. Since all the customer service needs you to log in... and I can't log in... it's a catch 22. I had to create this account just to ask this question.