Need help ASAP...

The vents on my series 3 AU ute seem to be stuck on the window demist vents and I'm getting nothing out of the face or under dash vents.
Wondering if anyone can advise me on where to start looking in order to fix it.
I've removed the controls and they all look fine.
Any help would be greatfully appreciated.
Cheers.

Would I be right in assuming the vent control requires pressure build up to work (Hoses connected and engine going to produce air pressure)?

YES, they run off vacuum.

Check where the vac hoses plug on at the rear of the BBM... Make sure they're continuous and unbroken up to and inside the fire wall...

One that runs behind the washer bottle is the BBM... One that goes down behind the motor is the heater tap...

Cheers,
Tim