Delay in House Possession

Respected Advocates, In June 2013, I gave a token advance of 15 lakhs to the builder to buy a home in Chennai. Initially , it was told that the registration would happen in July 2013, and I have signed the Construction and Sale agreement in June 2013. But due to various reasons (delay from builder side), the registration did not happen in time. The registration had happened after 18 months , ie in December 2014. The same agreement was used for registering the property. The builder had assured me that the property would be given for possession by March 2015. But, he had not handed over the property till now. In the agreement, it is mentioned that the property would be handed over in 18 months time . Now my question is , as the agreement was framed in June 2013, and June 2013 agreement was used, I would need to know from when would the actual 18 months get calculated ie from June 2013 or December 2014 ( the time of registration). If its December 2014, I would like to know if any action can be taken against the builder, as he delayed the registration for 18 months and then now taking 18 months to give the property. I have the proof of the builder giving a receipt when I had paid the booking advance ie in June 2013. As I am living in a rented home , I cannot wait for another 9 months for possession. Please advise.