Don't worry fella. I once had my email hacked along with my account. Luckily, I had a back-up email. So I contacted Blizz, scanned my ID and send them the usual form you have to fill in. Same day they merged the account with my main on it with my new Battle.net account and all was good.
Irony was.... I found out my old email got hacked by a chinese (the secret question changes language depending on where you from, and I got it in chinese). Damn you Chinese farmers..... damn you...