Builder Issue

I booked a 3 bhk flat costing Rs14.90 Lac under CLP in Sept 2006 in pre launch with Delhi based builder,paid about 71%of cost within 90 days of launch in Dec 2006.The housing loan was availed from HDFC.The flat was to be delivered in Dec 2009 i .e in 36 months of launch.Except land excavation project did not take off ,the builder blamed Economic slowdown and regretted delay,also promised to compensate for delay. Also promised to resume construction asap. I thought as builder was reputed I will get my flat eventually with some delay.I remained in touch with builder telephonically on periodic intervals over years and was given assurances only.Due to my posting outside Delhi I was not in touch builder for about one year or so. *I receive a reminder letter in Dec 2013 imposing holding charges,penal interest @24%p.a on outstanding dues,additional flat area,GST due to new law etc.The letter indicated I was sent possession letter in Sept 2012 . *The letter was never sent to me.The builder has not been showing proof of receipt at my address despite insisting several times. *I made a visit to Project site at Moradabad (UP) in March 2014 .Civil work was complete in particular block in which my flat was located,however,no lifts were installed,no wood work,no slab,tiling work,modular kitchen work,no flooring in one bedroom,no fittings in bathroom and kitchen and electric fittings inside flat were done besides other finishing work as per agreement.No liveable conditions existed with barricades and construction work all around. *I requested builder to complete the flat before handing over and remove all unreasonable charges and interest . *Builder is not responding despite my several visits and has forced me to pay Pre-EMIs totaling more than Rs 10 lacs. *Further I had made a disbursement request to HDFC Ltd in Feb 2016 .After a visit by HDFC team to the project they have replied in Sept 16 that flat was not ready for possession. *I wrote a detailed letter in October 2016 to builder bringing out all facts to do the needful to hand over my flat and remove all unreasonable charges imposed on me.Letter was sent by speed post and also by email. *Builder has ignored and not responded to my letter and continues to levy charges.Now builder has threatened to cancel my flat and forfeit money.Recently builder has also written to HDFC about cancellation and for issuing NOC by HDFC on builder’s discharge of my outstanding home loan.I have not made any default to HDFC till date.HDFC has asked my response. Kindly guide me for legal recourse for breach of contract and breach of trust in the circumstances. Regards