Landlord forcing extension of rent agreement and delaying the return of security deposit

Hi all, PART 1 - On 22nd Mar'21 my landlord has messaged me over whatsapp to vacate the flat by 1st Apr'21. 31st Mar'21/1st Apr'21 also coincided with the completion of 11 month long rent agreement. While I was open to it, and agreed to do so by 2nd / 3rd Apr'21, as the date got closer to 1st Apr'21, the landlord replied on whatsapp stating that, the date for vacating the flat - 1st Apr'21 stated by him was a mistake from his end and I need to pay a month's rent, even if I leave by 1st Apr'21 (I had already arranged my flight tickets, office leaves and hotel requirements to ensure I meet his deadlines of 1st Apr'21). Have 2 questions here: 1. Can the landlord go back against his word after asking me to leave the flat by 1st Apr'21? This is all over the whatsapp. Even the landlord has also stated - "I will not take [one month's rent] loss on a typo". 2. Does the 1 month clause of notice period hold true during the time of closure of rent agreement? I never had any discussion with my landlord on extending the rent agreement. Despite all our discussion, I had convinced my landlord of his unethical behavior and had vacated the flat on a positive note by 3rd Apr'21. The landlord has promised to return the deposit within a month (i.e. by 30th Apr'21). We had aligned on maintenance requirements and broad charges to be deducted from security deposit during the time of vacating the flat. PART 2 - However, now it has been 3+ months and he has not returned back the deposit. I gave him the leeway too due to COVID but, now after 3 months he is unnecessarily adding charges (eg: missing AC copper pipes). While the landlord has delayed the timelines, I am more concerned about the advantage he is taking because our security deposit is with him, which is unethical.