I Can't reach Battlenet - Blizzard entertainment

I bought Diablo (game from Battlenet - Blizzard entertainment) online about a year ago, got only a receipt and no CD-key. I want to log in from another PC and now my account is blocked. I can't contact support, because you either have to be logged in or know the security question. I can't find an email address for customer support. Whatt can I do? I've been posting on their facebook site, with no luck, The customer support system on the Battlenet site has a flaw in it. It goes in circles. Please help me urgently, I've been trying for 2 days now .