Change of construction plan

Dear sir, I have booked a flat in Kochi in 2015 and close to 60% of the payment is made by me, while the construction is completed only close to 40%. The actual date of completion as per the agreement of sale is October 2018 with a grace period of 6 months. The issue is the builder now proposes key changes to the original plan, while the completion of the project within the date as per agreement is highly doubtful. The changes he proposes are: 1. One tower out of the two towers planned is scrapped 2. Swimming pool, kid's play area and club house originally planned at the ground are now moved to terrace/ 14th floor of the building by scrapping the apartment in the 14th floor. The above changes are unacceptable to me as the building now faces the risk of vulnerability to earth quakes and the safety of my kid when playing on the top of the building is of a big concern. My questions are: The termination of booking from the buyer's end on normal conditions as per the agreement is 20% of the total price. Under the above circumstances Can I cancel my booking and demand refund of my money paid so far with interest and other damages? what are other damages or compensation I may be eligible to demand? Regards