If your account is every hacked or stolen, etc... This is what you do:

1. Call up blizzard support and tell them someone has hacked your account. Please lock it and request photo ID.
2. While on the phone with the support guy tell him to please change your email address (create a new email account). Some hackers, will actually hack your email and if you never deleted your email messages from blizzard, they will have your login and sometimes password. They can also do a password reset and gain access to the new password through your email.

3. Request they send an account retrevial form to your new email address. This form will require a photo ID and you can change your SQA, etc... through the form.

This is the only way to change 100% of your information besides your first/last name and hacker will no longer know your account info if it was compermised. :P

Then get an authenicator :P