Completion Certificate of Flats not getting from Builder

Dear Sir,
Please note that I have purchased a flat at koikhali one year back. But after reqesting again and again I am not getting Completion Certificate of the same. Presently a bank loan from SBI is going on for this flat. None of the flat owner of this building have got the Completion Certificate.

Please note that without this Certificate we are unable to shell our flats.

Please suggest.