this happened to me once. I bought an account and changed his email to mine. 2 months later I couldnt log in anymore. Checking the website and noticed that the email was changed back to his. So I contacted ijji and guess what, they didn't even give a F about my case. There's a way the previous owner can restore his information that is going through the compromised account claim. check ijji website and read it (in FAQ i think)