Delay in Possession

I have booked a property in Lodha group in 2010. The registration was done in 2012 June. Since then i am awaiting the possession. Background. While booking the flat in 2010, the possession was promised by Dec 2012, however for reasons which i am not sure the registry of the flat was carried out in june 2012 saying the possession will be by Dec 2014. During the registry period my loan processing took some time and for that they have charged me an interest of 18%. The interest paid was around 13,000. Now my question is 1. Since when should i demand compensation for delay in possession, i.e. from Dec 2012 which was promised when i booked the flat or, Dec 2014 that is mentioned in the registry documents. 2. What could be the compensation, the rent of the flat or the rent that i am currently paying. 3. What would be the interest applicable. I assusme since the builder has applied an 18% rate, the same should be payable to me as well. Pls. confirm. 4. Where do i lodge a complain as i now live in Indore and the flat is booked in Mumbai. 5. How much time would it take to come to a conclusion. Thanks Jimmy