Complaint against icici bank

I received a fraudulent call from icici where the fraudster had all the sensitive information which is or should be available only with the bank - ex : mothers maiden name, official email, and cvv etc. They assured me they are calling from the bank and requested upgrade of my credit card. They assured me that there will be a OTP issued only for the authorization for upgrade and no amount will be mentioned on it. As promised by them, there was no amount mentioned so I trusted and gave them the OTP. I was charged 40,000 INR for this mistake. I then realized and filed complaint with cyber crime and called and reported the incident to bank and blocked the card. All within an hour of the incident. The bank is now demanding that I pay my credit card fees and pay the 40k which was already reported as fraud. They are not listening or behaving professionally. There are many loopholes in this pointing to fault at icici but they aren't taking any responsibility. I'm being harassed on phone and in person when I visit the branch. Seeking legal help to take this against them and protect others who are in similar situation as me.