Possession

Paid 90% and final 10% was to be paid on possession.They didn't issue any formal possession letter or CC just sent revised demand notice with extra sqft for adjustment on delayed penalty of only 6 months @Rs5/ft actually 3 years delay. We wrote mail asking for issuance of possession letter and CC before asking for payments but no reply. We filed a case in NCDRC where case has been admitted but date is in Oct till then what do we do to take possession. They are also insisting on deed of conveyance to be singed which has clause like everything ok, no due , all satisfied and no legal later.We are waiting for their reply to NCDRC within 30 days which they may or may not..my question : 1. When is possession date considered legally ? the day builder says or day he issue's possession letter with CC or CC status 2. How to take possession without one sided clauses in deed of conveyance ? 3. Our complain includes - major quality issues, delayed compensation and less sqft delivered compared to what actually booked , missing amenities 4. Can there be police case as he is not sending possession letter and CC and giving possession ? also deed of conveyance a factor