Haven't received the barcode for taking biometric info.

Hi I am an international postgraduate student and I've applied for extending my Tier 4 visa. Last Friday I received a letter from home office which mentioned that I failed to give them my biometric information within 15 working days. However, I haven't received any letter before including acknowledgement letter. The letter I got also indicated that I have 10 working days to have my biometric information taken, but I haven't got the BARCODE which I supposed it would appear on the original notification letter. So I can't do anything right now. I've mailed to their given email address last Saturday, but I haven't got any reply yet. The deadline is tomorrow, what should I do? It is really urgent and I really need your help. Thank you!!