Possession without work completion

I have bought a flat in Hyderabad. I have almost completed my 82% of total payment at the time of sale deed. My 10% of total amount is due on flooring completion and rest on flat completion. From Nov 2017 onwards builder has sent me demand letter two times stating that flat is completed. After my visit to flat there are lot of issues pending which includes few of flat specific and majority of amenities specific issues. I shared them a list of issues pending on 2 nd Jan 2018. As soon I shared issues and cleared that I am not going to clear any amount. They sent me a notice from a advocate stating that their flat was completed fully and i need to clear full money along with penal interest. Moreover notice charges also to be beared by me.afterwards they agreed on mail communication that , release flooring charges as per agreement. Occupancy certificate still not shown to me after many mails by me stating to show occupancy certificate.moreover they are not taking care of any issues they are saying will be done you release amount related to flooring completion. My question is what to do with this notice does it still consider valid? And how to deal with the situation. Please suggest