The Crystal Castle Approvals issue

Q: I have booked the 2BHK flat in C wing, The Crystal Castle, Dhayari one year back in July 2011.(Multicon group project)
The below commitments were given to me because of which I did booking of flat
- Agreement will be in Aug2011
- Possession will be in May 2012

Till date, still my agreement is not done and progress of construction is also stagnant till 4th floor from last year.
From last year, every month, when I am asking builder, he is saying that some issue with plan approvals from PMC and he is following. But he is not even committing on agreement or expected possession now as it is pending in PMC and not sure when it will be approved.
He is not even explaining the issue why it is pending.
If I will withdraw the booking, the rates are almost increased by 1000Rs persqft due to which I will be in loss for minimum of 8-9 lacs for the same area.
Please advice me how to handle this situation legally.
Thanks in advance.