1. You can file a Police FIR, requesting investigation and charge-sheet, for offences like Threatening, Cheating, Intimidation, Fraud, Breach of Trust, Mischief etc.... against the person, supported with all relevant supporting Documents, Evidences & Witnesses.
2. IF the Police does not take action, THEN you can file private criminal case u/s 156(3) Cr.P.C., in the local Magistrates court, seeking directions to the Police to investigate and file charge sheet. The said Person may come down for settlement.
3. You have an positive option to file a grievance petition against the Builder /Developer, in the local Consumer Court, for their illegal trade practice, negligence, deficiency, harassment, intimidation, cheating etc.... with proper documentary evidences and you can claim damages /compensation & interest on your investment, and for your physical & mental trauma.