i had deal with blizzard help line 2 times when my fwen's WoW account was compromised about a year ago

they had asked few things from me to verify that I'm the 'legit' owner (in which, i'm not...) by requesting few items like answer to passphase, cd keys or few legal copy of your work id/ identification card to prove you are who you are

seeing such scenario, i would be wary of you to win the fight if you only provide cd key to them while your seller provide his id that matched the profile.

even if the person is putting fake information in bnet account, there is still potential risk of your account being hijacked by the original owner, when he is the one who created the bnet AND the email that attached to it.

certain mailing service provider have implement certain security behavior to let the original owner take control of that mail. you might have 'lost' the bnet account tug of war when he can abuse such email feature and claim back the mail, thus indirectly control the bnet account.

low fast can you change your name, compare to changing password?

by the time you change your ic name, the dude might have moved the bnet account to another email weeks back (time is judged by how effective our gomen department is when no $$ is involved...)

logic wise, would you change your name from 'lee ah kow' to 'mohd ridzuan bin mohd kasim' just for a game?