thank you all for the replies.
I did contact the Council in numerous occasions and even some of the guys form Right first time. The problem is that non of them has a clue of where the water supply can be switched off. I know where to with the one in the kitchen and the sink in the bathroom as well as the water to the toilet but for some reason nobody can find the stop to the water supply to the bathroom sink.
The plumbers I got in both told me that even if the council did switch the water supply of the all block off off, which they can for a feee, it would not help as there would still be water in the pipes. coming from the other flats.
It would be so much easier if somebody had the plans, drawings or something related to the building and could maybe shed a light to the mystery of where and how to switch the water off. I cannot believe the council does not have plans and is unwilling to help. If I did have a leak in the bathroom, hope not, somebody would have to act and fast to avoid flooding the flat underneath mine.