Hdfc - Fraud call in the name of HDFC debited money

Hi. I'm working at T.nagar... yesterday (**th July) while I was at work, I received a call from a lady who addressed herself as a HDFC executive who is responsible for changing the customers credit card from annual fees to no annual fees card.. I said her tat I won't share my otp and stuff. But she was too bold to tell me things tat an executive would say.. she told the correct first * numbers of my card and made sure I believe her.. she also said me tat it is so safe since they are calling from head office.. she even connected me to an IVR to make me tell my CVV. I was totally blank and stressed.i couldn't even walk home. This is not a lesser amount to move on. Even I don't have money for my own use I would pay the bill before date. I was using this card so carefully. I need HDFC to take action on this and do me the needful. I've also informed police about this cheat.. I'm totally down. Also I request bankers to make customers get some basic information about fraudsters because I'm an educated one but still I can't find the difference in her speech... I want others to be safe and aware so this don't happen to anyone..