HDFC credit card - Harassment after clearing dues

I was not receiving my credit card statements on email and made payments based on sms due amount month after month. when they suddenly asked for a large sum due, I was stumped and asked for the missing statements. they provided that after months of follow ups and jumping through hoops. And i clarified with the follow up agent that since the other interest and charges are not due to my mistake, i would pay the legitimate dues and close the card. they agreed, I made the payment. After that they are constantly harassing - insisting that i have been issued another card and there is outstanding dues on that. Repeated emails, letter and complaints to RBI and ombudsmann has not solved the issues as yet.