cancel development agreement and development power of attorney

Issue legal notice regarding cancellation of agreement followed by a suit either for specific performance or declaration, permanent and mandatory injunction through a local prudent lawyer.

You can also file a police complaint for fraud and cheating.

You have additional option to move to jurisdictional consumer disputes redressal commission for deficiency of service. 

you may file a consumer complaint before the NCDRC and simultaneously file a criminal complaint to put additional pressure if sufficient grounds are made out.. Yes you can terminate the contract without paying anything to the developer.

 you may definitely cancel the agreement. Send a letter to him for the cancellation of the construction agreement. there will be no legal complications for you since the builder has not completed the project on time.