The truth is that we have too many numbers. Generally, its easy to put pressure on the government by forming action committees of affected people and forcing prioritization of certain projects ahead of others.
But given the vast numbers of people in Mumbai, its hard to form a substantial coalition that can focus on a single set of issues.
My solution is to break Mumbai up into smaller municipalities. Each of the areas Dadar, Worli, Parel, Andheri etc. are big enough (population-wise) to be their own city. Its impossible to get the BMC to prioritize projects for such a large set of towns.
As for the slums, I think its impractical to think we can simply bulldoze them and the people will just go away. Its a sensitive issue. No one wants to live in slums, but no one wants to starve either. People willing to work and who earn little are many times forced to live in slums.
The government is not only incapable, its made up of people like us. Its hard to get them excited about things that are not sexy.