1. The total price of the flat was told to you or was written in the brochure or some other document which is less than what has been mentioned in the Agreement?
2. It it was verbally told and there is nothing in writing, then immediately put the discrepancy on record by posting him a letter to this effect and asking for either a fresh agreement mentioning the earlier assured price or refund the amount paid by you immediately,
3. If he does not refund the said amount, you can also lodge a police complaint against him for cheating you,
4. Also can file a complaint case before the local District Consumer Dispute Redressal Forum against the Developer alleging deficiency in service and unfair business practice claiming refund of the amount paid with interest, damage and suit.