Owner not willing to give deposit amount, even after providing 1 month notice period

We had moved into a 3bhk flat and had a agreement for 11monts. Due to covid situation we were going through financial issues so we asked our owner to reduce 50% of the amount if he can but he agreed for 15% of rent which we were still very grateful about, also both the parties agreed on that the amount is to be reduced since we won't be able to return him the reduce amount later if he ask so. So from August onwards we were sending him the rent in advance as agreed. In the mean time we were not informed about the renewal of the agreement or any notice to vacate the place so we were also not aware of expiry of agreement . So the agreement is expired on sept and we were paying as usual. But now due to circumstances we have to vacate the place and so we have provided 1 month notice period to the owner. But he told us that he won't return the amount and also he will deduct the previous amount also from our deposit. So we asked him to deduct the last months rent from 65k but apart from that we would expect all our deposit back. Please help what options do we have.