So I also got a call from such a scammer. Started with a lady and then she handed the call over to her 'Manager'.
They knew my debit card number already which is a VISA card, and they knew my name and all. They said that they are gonna change the debit card as per regulations of RBI.
So I was almost convinced. Then the guy said you will get an SMS and you need to reply to the SMS, I said OK.
Then I got an SMS saying there is a transaction and I received the OTP. I asked the fellow what kind of SMS is this, he said its a fake transaction, you need to tell me the OTP.
I politely asked him to sod off and told him I am reporting his number. I called ICICI and reported his number, they thanked me for not divulging more details, called me very smart and told me that appropriate action will be taken against the number.