Rera

The applicant purchase a land from builder he didn't got his project registered from rera and gave undertaking at time of saledeed that he will get rera registered in one month which I came to know after saledeed executed The registrar didn't deliver saledeed and hold it due to not registered in rera. The applicant file case at rera authority for delivery of peaceful possession and compensation but now builder is taking stand that he had return back sale consideration to applicant firms which actually was payment of building material which builder purchased from applicant firms. Now my submission is saledeed can't be canceled even sale amount is returned though I don't admit it. It's registered document and can be canceled by registered document or civil court of law. The authority chairman is going prejudice and not hearing my complaint but setting enquiries on my papers though builder had taken GST input on building materials which I supplied to him. The rera authority chairman is neither completing order sheet which I can challenge nor he is listening to me. The chairman is retiring on April 2021 and I have feeling that he will definitely go wrong and prejudice. Kindly guide anyone. As rera is new my advocate is civil lawyer and he is replying every query but chairman is not listening. Please help. Thanks