Do you mean SBI Securities, a Japanese Internet securities broker, by "SBI"?
If so, try following telephone numbers in Japan. They may have English-speaking staff.
If they don't have, write and send a letter by airmail to the address below with a notice like "I want to open my account in your company." on the envelope.
SBI Securities Co., Ltd.
Roppongi 1-6-1, Minato-ku, Tokyo 106-0032, Japan