Pavement encroached in front of my office building?

I have one portion of office complex in a three storied building. But the whole length of the building front about 150feet is encroached by party offices, tea shop, fast food and so on. I dont know who are the occupants and now they even gone to the first floor with ugly structure and blocking the view of the office building and all the ktichen exhaust directed towards my office building. on account of this I am not getting any one to take it on rent or no buyer coming forward.

So can anyone pls suggest best means to tackle this and pls take note that I need directions based on Indian legal system taking into consideration that the encroachers details not known.