I've registered my NGO as a trust in India. Do I need to separately register for tax exemption? Also, should I get a trademark for my NGO's logo or is it automatically protected by the trust registration?

You can issue a legal notice to Indiahomes demanding the credit note and profit sharing as per the August 2015 agreement. The notice should be sent through registered post with acknowledgement due, outlining the breach and demanding compliance within a specified timeframe. If they fail to respond, you can consider filing a civil suit in a court of competent jurisdiction.