Builder Has Not Provided Car Parking, Generator To Lift As Per agreem

I purchased a semi finished flat from a builder and got registered in my name. Under another agreement he completed the construction and handed over it to me. I paid the amount to him as per agreement. So far he has not marked car parking space to any buyer and not provided generator to the lift as per agreement. He is not responding to our request to provide the same though the flats were handed over to us one year back on the ground that some of the buyers did not pay the amounts in full which is being denied by those buyers. Nobody is interested for tenancy of my flat for the lack of the above facilities for which I am financially loosing. What shall I do?