Chawl issues

Our neighbours have reconstructed their house recently the issue is they have taken the height of the house from ground level atleast 2 feet. For entering the house there is a need of 1 stair but theirs other neighbours are not allowing them to make one. They are claiming that that small passage (outside the house ) belongs to them. I think the space in front our house belongs to us. Is there any way out for this problem.