TASHEE LAND DEVELOPERS PRIVATE LIMITED - Flat not given as per allotment letter

I book a flat at Capital Gateway, Tower A, *th Floor, area **** sq feet. as per the letter of allotment dated **th December, **** to hand over the possession within ** months of the sanction of the building plans and other government approval. However, after lapse of more than ** months, I do not have any knowledge of when will I get the possession of my dream home. The builder is not reachable in office, does not attend phone call. The copy of allotment letter along with the Tripartite agreement with the banker, builder and my self is enclosed.