Delay in Posession

I seek your valued advice. I had booked a flat in residential project of Ansal API in Sonepat in 2011 and had been paying regular installments as & when demanded. Last installment was paid in Nov 2014 . Thereafter no demand has been received and no construction has taken place except for initial basic pillars structure upto 5-6 story's in a 13 story tower particularly in two towers including where my flat is. In other towers some minor activity has been going on. The possession was due in May 2015 as per agreement. Due to delay in completion, I lost my interest & requested for refund of my money with a reasonable interest. The company accepted my request and agreed to pay as and when funds are available. Despite several reminders and personal visits, no payment has been received so far. Can you advise me the best course of action to retrieve my money. The project was already ongoing when RERA came into effect and is not registered with RERA through checking the Haryana RERA website(Panchkula jurisdiction) as of December 2018.