Jain Housing sunderbans west mogappair
Quality of flat and Penalty issues

We bought a flat in Jain housing Sunderbans west mogappair. They are not handing over the house with quality. They collected the penalty of about one lakh from us for one month delayed payments. But there is no penalty for the delayed completion of flat. They delayed the completion of flat by six months. Any suggestions to proceed for this legally is much appreciated.