Penailty for delay payment

I booked flat in supertech eco village Noida extension in 15 may 2011 and I paid 10 percent amount by chq ,I got booking form mentioned unit numbers,my plan was down payment plan so after 30 days I was suppose to pay 85 percent amount which was 13 lac,sudendly in Noida extension within month farmers land acusition problem started and court holds many projects and there was farmer protest ,I 2-3 times in mailed and called supertech for my builder buyer agreement but they said nothing is working till court orders comes as all agreement work is on hold and in oct 2012 I got demand letter for 85 percent payment and I made payment and got agreement of builder buyer now in 2019 they are demanding 5 lac penailty for that 9 month delay payment between june to September @24 percent please guide me without demand letter and builder buyer agreement I would have paid amount of 85 percent even I mailed them for agreement but they didn't give ,I got demand letter of 85 percent payment on oct 2012 and I paid what should I do please guide.am I faulty..also period of may 2011 to September 2012 is zero period and authority also said no interest builder should charge and even authority didn't charge interest from builder