Occupation certificate not provided by builder

I had purchased a flat for over 2.5 crores in Oct 2012 at Mumbai with a reputed builder and the OC was expected as stated by builder agreement in April 2013. This is as of date, 1 July 2015 pending. After filing the RTI it was understood that the builder has provided the wrong coordinates towards height. This is in the secondary flight path and the building appears to be above the permissible limits. The CC and plan is fully approved by the BMC upto 14th floor. This has received partial OC up to 12th floor, the 13 and 14th floor are yet pending for OC while the flats are fully ready. No amount of conversations with builder has yielded results and my lifetime savings is now appearing in deadlock. Am not sure if occupying the flat will weaken my situation in filing a possible complaint. What is the typical timeframe and what is your view as a litigated property cannot be sold so I will need to then hold on as there will be no alternate. Should I file a complaint in the national consumer commission. No compensation has been paid by builder and am losing out on tax benefit, no rent and neither can I occupy the flat and have to pay for towards the loan.