Owner Has Threatened To Not Return Security Deposit And Also Called Oversmart

My lease and licences agreement is about to end on 31st August. Had already talked to owner on phone that we do not have any plan to renew/extend the agreement. Everything was fine and had decided to handover the keys to owner by month end but now suddenly the owner is like you have to fix the seepage problem (ceiling of the washroom) or we won't return the deposit. When I said it is due to external reasons since it is on the ceiling and we haven't create that issue the owner changes the reason that since we are not staying in the flat is locked and they are not able to show the flat to any future tenant. I said I am out due to some personal issues but will definitely handover the keys by 31st. The owner is adamant on not returning the security deposit. The rest for all the 11 months is already paid online and even the electricity bills are paid.