Where does their headquarter locate?

http://bulbrokers.com/en/

Bulbrokers is owned and operated by Bulbrokers EAD, a company licensed and regulated by the Bulgaria Financial Supervision Commission (Bulgaria FSC) 

As for the question you asked, we indeed found an address on the broker's website. But we still recommend that you ask the official customer services directly for a more accurate answer. For more details on this broker, please check our full Bulbrokers review.