Delay in Property Possession and Maintenance Charged by the Build

I have purchased a property in Greater Noida in 2011 which was supposed to be handed over in November 2013 (in 30 months). The construction is still going on and possession is no where in picture. The buyer builder agreement has a clause that if the buyer default in payment then he would be liable to pay interest on the particular installment. Interest charged is 18% per annum. The Buyer would pay 5 rupees per square foot per month for delay in possession. Please help me clarity the following points. 1. I had paid 2 installments after the due date for which builder has charged interest which was duly paid by me. Now the builder is not ready to pay me the charges due for delay in possession due to the above grounds. Can I file a case in the consumer court to claim the charges. 2. The builder has started charging the maintenance charges from August 2015, is it legal to charges maintenance prior to possession. 3. I have paid the entire amount for property registration in August 2015 and signed the stamp papers in October 2015. The registry has not happened and I have been following up with the builder on emails and phone and also visited personally without any progress. I am very frustrated for last 2 years and the builder doesn't seemed to be bothered. Please help to explain the legal remedy available for me to file a case against the builder. Thank you for your response.