Landlord not cooperating.

Dear Experts, I am senior citizen and recently have rented a flat in Navi Mumbai, On the first day itself there were vibration and loud noise from bedroom flooring, seems the problem with below floor cieling fan, i informed the owner about the same and his property agent checked it , but the tenant on below floor is not cooperating to get is rectified.. Owner has now switchoff the phone from past 2 days and is not contactable. Inspite of several calls and messages owner is ignoring it. After 10 days, yesterday i sent him a Whatsapp message informing that i am vacating the flat with 30 day notice as per clause mentioned in leave and license agreement. Owner is also lieing about his present location, 3-4 days prior his son in law and daughter picked up the call and informed us that he is in Murud (kokan area). Yesterday his property agent is informing that client is gone to USA. I have few queries would appreciate your advice. 1) Agent has not registered the leave and license agreement, it is on 100 Rs Stamp Paper along with police verification form. 2) Though i have sent him vacating notice on whatsapp, it is not yet delivered because landlord is not switching on his phone and i don't have his alternate contact number. 3) I have decided not to pay him rent for March month and electricity bill and would ask him to deduct from my security deposit. My last day for vacating flat would be 30th March, 2021. 4 I feel that the landlord might not collect the keys from me on last day and not return my security deposit. What steps can i take if the doesn't collect keys and not return the deposit amount. Please Advise Thanks in advance.