Deny to refund security money and talking very bedly

I had rented a room/flat at Sheetla Residency, for which I paid an advance rent of one month along with a security deposit of Rs 12,000. Now the owner is refusing to refund my security deposit. He is insisting that I must stay for one more month, even though 20 days of the current month have already passed. I have already paid the advance rent for this month, so I do not think I should be forced to stay an extra month or lose my deposit over this. I request that the owner refund my security deposit of Rs 12,000 without forcing me to stay beyond the notice period already covered by my advance rent payment.