Builder not likely to complete project by possession date

I have found various cases where builder has either delayed or has not given possession. I am facing a different nature of problem. I have booked a tenth floor apartment and the builder has issued a provisional allotment letter stating that possession is expected to be delivered by march,2017. Inspecting the site, I find that the project has reached only till basement level and by any stretch of imagination construction can not be completed till third floor by march,2017 and under no circumstances my tenth floor apartment construction be reached resulting into deficiency in service & breach of giving possession, which is likely to be after at least four to five years as informed by builder's staff . I am 72 of age and getting possession by the time I cross 76/77 years of age is of no use. In a few days the builder is going to raise demand of Rs 25 lac on laying the roof of basement. Can I stop payment of this demand and further demands, so as not to block my money in this age which will be long drawn process to recover later. Can I file a complaint with Consumer Forum to claim my money (65 lac) back in view of incapability of builder to complete the project up to my floor.