1. Call Blizzard at their number. Don't bother with Singapore's line. Call US direct.
2. They'll ask you to verify a few things. Any codes of your previous purchases, (inclusive of Starcraft, WoW, etc) and you'll need to validate your identity by sending them a soft copy/fax of your valid ID with address (I sent them my IC)

Wait for 3 days. That's how long it took for mine.