Builder demanding for interest for late payment just before poses

I had done agreement with builder and made all my own contribution(20%,ST,VAT,SD,Registration) within 2 week of agreement. On his request i took help of his agent from SBI for my loan , that person delayed my work and finally flew away with my documents. A new Loan application was filed and this all delayed the Loan Sanction and disbursement. Even till last week i inquired he said your only maintenance money is left and you can take possession then. After paying that sales person is now saying that you have to give interest(1.65 lakh) for delay in payment(although from bank). Below are bullets: 1. I have made all my own contribution on time. 2. Have given full support to bank agent , kept following each day. 3. Till day Sales person has not told me about any interest else i would have done something about that. 4. I gave him 3 customers(although on humanitarian grounds), he should at-least consider that. It seems to be cheating as person who is eager to get possession of his flat would try and settle with him, as is told to me give in cash and we would settle. Please advice.