RBL Bank — rbl bank not cancelling my credit card despite multiple requests

Rbl is purposely trying to harass me since i have raised credit card cancellation request. I have already paid all the dues and submitted credit card cancellation request. Every time they close the request saying they could not contact me but that is wrong. Even i changed my registered mobile number when they said so still they close the same mentioning same reason. After 14-15 days of continuous chase, rbl executive from retention department called me back and i clearly asked her to cancel my card and she later accepted the request and said i will get confirmation mail within 3 working days. Now after 3 working days, they again sent me a message on my registered mobile number saying they could not contact me. This is a clear harassment. Though i have all the evidences of requests, dues, call recordings etc. I can provide if needed. Thanks.