Also I haven't played for over a week, so I am bemused how someone logged in...
Same happened to me a few weeks back - I'd not played in months and wouldn't have even realised my account was compromised if I hadn't got an email from Blizz saying my account had been suspended. I contacted them though and got my account back, plus loads of items returned via in-game mail to multiple characters that the git must've sold or whatever.