Realtech Nirman Private Limited - Realtech Nirman Private Limited Unreasonable delay to complete the pending work of new property THE

I booked *.* bhk flats in The INDIANA property from Realtech Nirman in kalikapur, newtown, Kolkata, and possession date was Dec ****. But due to covid they got an extension from HIRA till Sep ****. And at last without complete the many types of work they started processing and I registered my uncompleted flat on Jan **** and they told the pending work will finish by next * months. As per HIRA all work includes amenity should be finished by Sep **** but still many types of work are pending and because of this I did not shift to my own flat. They are telling we have funded shortages so until **% sold we cannot complete the pending work, so Where is our fault, if flat is not sold out so why we will suffer. Now there is no news about pending work. Throughout the delay they are supposed to provide % interest (as per agreement) & monthly rents which they did not provide. Moreover, the entire team is extremely unprofessional with no response to messages, mails or even calls. It's been a nightmare dealing with them. Need help to get my flat asap along with compensation if possible I want complete refund with interest because they did many changes on the complex many illigal construction they Made and make very conjusted this complex.