Problem with my WoW account..?

Yesterday i was checkin my email and noticed this one from blizzard informing me that i successfully merged my battle.net with my WOW account.

The e-mail had my first name wrong and i dotn even have a battle.net account.

Obviously i got hacked, even though i was as careful as i could with everything regarding security. I never got hacked nor had anything stolen online in the past, i see a problem with this system that pretty much allows the hacker to chaange my password by mergin with a battlenet account, since all they need is a password, after that they control my account.

This issue is really urgent but Blizzard's billing department doesn't work on sundays so i'm looking for a way to solve it ASAP, is it possible for me to get any help today?I think the more time passes the more it will take for me to solve it later like gettin chars/ items back.