Builders raising demand notice before loan approval

Hello i have recently bought a flat and have paid the 20% amount and applied for 80% loan. Since the loan has been applied from a PSU bank, it is taking really long for the loan to get approved (already 2.5 months including a lot of holiday period). The builder has raised a demand notice for the amount payable which as well includes the interest amount. After having talked to the builders it appears they are not interested in waiving off the interest (though confirms only 50% of the interest amount demanded is needed to be paid and therest can be waived) inspite of the fact that approval process is something we cannot influence. My question to you: - Can the builders raise a demand notice even when the loan is not approved ? (agreement does not mention when the amount is payable, rather mentions that payment should be made strictly based on the completion % and since 80% of construction is finished they are demanding 80% loan amount + interest thereof since the very next day we paid the initial 20%). - what are the course of action with me if i do not want to pay the interest amount at all? (agreement states "builder to send a notice by registered post or by courier giving 15 days time to make the payment and if the PURCHASER still fails to pay, then treat a sum equivalent to 10% of the cost of the Apartment as forfeited and adjust it as liquidated damages from and out of the monies paid by the PURCHASER and rescind this Agreement.) - what action can i take against the bank for the delay and if i can recover the interest amount from them ?