Sandhya Nagari 11 - Owner is not refunding security deposit

I was staying in a rented house since August **** and vacated that in March ****. The flat is a very one, with no lift and walls were not painted for ages. The rent agreement was done for ** months, i.e. from August **** to July ****. After that, the rent agreement was never renewed. It was communicated by an owner that once this covid situation gets over, we will renew this and also, informally communicated that the rent will be the same for the period from July **** to June ****. Now when I had vacated the flat and asked for my deposit to be refunded, he is telling me now that he will consider a **% increase in rent from July **** till March ****. When I told him that it was not informed, even informally, how can he increase the rent from the past date? His answer to this was “It is common sense! I have exempted you in *nd year and as there was no renewal of rent agreement, so I had not informed you.” I told him if you would have told me at that time, I would have either considered the increased rent or would have vacated the flat at the same time, considering the rent and flat condition. And, it was pretty clear to him and that’s the reason he intentionally didn’t ask for the incremented rent. Every month on day *, he is getting the rent and he never came back asking that I am expecting a **% increased rent from next month…
It is not expected from an educated person to say this idiotic thing with no logic!!!