Real Estate Harrassment in telangana

Hello Honorable Lawyers, I had purchased a flat from a real estate company in Hyderabad. As per AOS, they are supposed to deliver the flat by march 2019 that is including grace period of 9 months. I had believed in their words that they will deliver the flat before time and accepted on AOS to pay interest of 9% if I delay payments and they would pay Rs. 3/- per sq ft if they delay in delivery. There seems a lot of deviation from construction plan and they cannot deliver it on time looking at the progress and they are pressurising me to make further payments and threatening me that I should pay late payment charges as I had stopped further payments after paying 43 Lakhs. This real estate company is unfortunately not registered under RERA and they are not ready to pay rent if the flat delivery is delayed even if I m ready to clear dues. As my investment is completely locked, and Kindly suggest how to deal with this reputed builder.