Sounds like the car has been chipped but hasn't been set up properly. You could always remove the chip temporarily and reconnect the AMAL valve to see if the buzzing stops and whether you get any overboost.

My AMAL valve clicks continuously when the superchip is plugged in - but it still works properly. Are the vacuum pipes still connected to it? If it still doesn't work then it points to a fault somewhere else.

If it does work you may find its faster already. You could then put the chip back in, disconnect the AMAL valve again and turn the actuator up a touch until you get the correct amount of boost. You should really get it set up properly though.