Unfair demand of interest by builder

28- May-2018 - I received demand letter from builder for payment of whole amount and gave me a time for 15 days for the payments i.e. 12 june 2018. 30-May-2018 - All documents submitted to builder for loan purpose. 12 June 2018 - Loan sanctioned by bank and intimated to builder. 18 June 2018 - BBA agreement executed by builder and handed over to me on 22nd June 2018. 22 June 2018 - Request submitted to builder for tripartite agreement. 25 June 2018 - Tripartite agreement handed over to me by builder. 02 July 2018 - Final Disbursement of loan was done by bank. Now my builder is demanding for interest @15% + GST for delay of payments by 20 days where i am not a defaulter. After final words with builder he is asking me to pay interest @8.35%. Please tell me whether i am liable to pay this interest to builder or not as i don't have any mistake in this. Loan disbursement was not possible without BBA agreement and Tripartite agreement. Builder made intentional delays just to grab money