Security Deposit

I am a tenant. My 11-month rental agreement expired in November 2020. However since both the parties agreed for an extension of contract, we stayed in the residential premises post November as well. This contract mentions notice period of 2 months, but no clause saying that failure to serve the notice period would lead to non-repayment of security deposit is included. The landlord took the responsibility of drafting the renewed agreement, but no such written document was produced to me. So post November we have been operating on an oral rental agreement. However, due to termite attack at the house and failure of landlord to get the termite treatment done, we had to vacate the house in the last week of May, with an oral notice of 2 weeks only and was agreed upon by the landlord. It's been over a month, since we vacated and the landlord hasn't repaid our deposit. In fact, he is threatening to repay only 50% of the security deposit because the 2-month notice period was not served. On what basis can I get full repayment of my security deposit?