Unitech Group — unitech cascades - greater noida, not releasing possession of my flat.

Address: 6, Community Center, Saket., New Delhi, Delhi, 110017

I have booked a flat in unitech cascade greater noida, cascade tower 4 1103 flat no.. I'm continiously following up continuously folowing up on getting the possession, unfortunately i'm unable to get any update from the unitech team.. Now the situation is that nobody is in the office to give any update on possession neither in office nor in society. I have visited many times to their office and society but no success till date in getting any sort o[censored]pdate, there is no authorized person to deal with and despite with 90% ready, the builder is showing no eagerness to complete the job. I can also see that their staff are removing already existing accessories from the flats where ever they need one.
Even in tower 4, in 6 of the flats people are already started residing.
I'm surprised how they got the permission to stay.
Need your help in getting this issue resolve.