AU BANK FRAUDULENT CREDIT CARD TRANSACTIONS

A call was received and caller was said that she is from AU Bank and said about my card last four digit and my card limit so I believe and after that she told about reward point redemption and installed some illegal site for convert of reward point . I donot understand that time and installed that, in few minutes they compromise my mobile device and generate otp and taken Login ID and password , also after that increse limit and transaction done around at 1919 and 1920 hrs, after that I informed to AU Bank about my fraud around 7.21 and card blocked mail received at 1925 hrs, subsequently complaint to Cyber 1930 No. and acknowledgement received at 1932 hrs. , but bank told in closure report that Each transaction was verified through OTP sent your registered mobile no., entry of OTP confirms that the transactions was authorized and acknowledged by me. same in rbi closure report