1. You have not provided with complete facts of the case,
2. You have bought the flat or executed an agreement for sale?
3. If you have executed an agreement for sale with the allotee, did you makie the builder a party in the said agreement?
4. If yes, then all of you shall have to abide by the terms & conditions mentioned in the said agreement for sale,
5. In case the builder violates any terms mentioned in the said agreement for sale, then you can file a complaint case before the local District Consumer Dispute Redressal Forum alleging deficiency in service and unfair business practice claiming immediate possession and registration of the flat after collecting the amount agreed by all the parties, rent for the delay, damage & cost.