need help regarding biometric appointment letter

[knv]

Hai all

I had applied for tier 4 visa extension. I have submitted my application on 31st of October 2011. After couple of days I received conformation letter with a reference number on it
i haven't received biometrics appointment letter till now. its been like 4 weeks. can anyone please suggest me what step I have to take.

is it possible to book an appointment without case reference number or do you want me to wait until i get that reference number.

is there any other way to enquire about it.

thanks in advance