It could be he is trying to scare you into stopping drinking? I don't know but I have trouble putting faith in doctors etc. Anyway I am not giving medical advice but do you hear voices when you drink or when you quit for a few days? I visually hallucinate when I try to quit maybe you auditory hallucinate?
Doctors aren't gods but to quote you
'Maybe it is down to the alcohol, I guess this is the first really constructive thing they have suggested!!!'
I would say that is a real big possibilty.
I used to do acid and mushrooms and the visual hallucinations don't scare me (the withdrawal visuals)but I had a breakdown a few years ago and 'heard' the TV and radio talk to me and that was more scary than the DT's by far.
Perhaps ask to be referred to another psch? There are good and bad ones you know.