BPTP charging interest of late payment due to not providing document from their side

I bought a flat from so-called ‘reputed’ builder BPTP in sector-81 in faridabad. After payment of down payment, I choose Construction linked payment plan and avail a Home loan from HDFC bank. I submitted the sanction letter of HDFC loan to the builder much before their demand against further construction. When the demand raised by BPTP, my bank refused to pay the money saying that documentary formalities are not completed by the builder, they required few vital documents to disbursement of loan. I asked BPTP and they confirmed that some documents are pending and they will provide to my bank shortly. But it took more than 1.5 year to complete the documents and bank disburse the demand amount. Now BPTP is asking me interest of delayed payment which they themselves delay. Please help