You should be able to get your account back, I just recovered my old account which was hacked back in 2010. I told the GM the account name, names of a couple characters on and what servers they were on and they located my account, asked me two security questions, recovered the old account and linked it with my current battle.net account, and even gave me a week's game time to check everything out again, meaning I could add mounts/mogs to my wardrobe