Air Force And Naval Housing Board — 1. Late handing over of flat 2. Extra cost

Address:

Mohali, Punjab

Sir,
I have registered for a flat in afnhb project at mohali, in year 2008 and got a flat allotment in nov 2009. I have paid the amount called by afnhb with in three months (Rs12, 50000) , the amount called up by afnhb till that date. And after that also i have paid all the called installments on date.
A) initially, the flat cost was 14. 72 lac, but increased to approx 16. 43 lac. And now when they are handing over the flat they are asking 19. 70 lac approx.
1. Is this legal to increase the cost by nearly 30% and ask more amount when completing the project?
2. What should i do?
B) the initial time for project completion was by 2012. But they have delayed the project by 03 years, is there any rule by which i can ask for compensation ?