How do I deal with a neighbour from hell in a block of flats.?

freehold propery-leasehold flat. 12 shares 2per3bed flat 1per2bed. she has 1 share . No respect for due process,abiding by magority vote,sends threatening to sue letters to management committee which are the other residents. Their ability to run the property is undermined by her attitude of selfishness , not listening to others , complaining and her demanding "i want - I get". When new neighbours move in she immediately has a go at them for overloading the lift, making to much noise -walking on the floors- parking in her places , she has no car - the hall needs redecorating,new carpets, only ten years old. we have just had the garden relandscaped and she did not like the contracter so she took us to a tibunal ,which she lost but this does not stop her. It is making sale of flats extreamly hard. This is making life intollerabe for all other residents. What can I do? I can not move as i care for my elderly mother. What can we do?