[Resolved]  Kotak Mahindra Bank — abn amro card used in 2007 and paid all due and closed now (oct, 2017) now (oct, 2017) recovery agent asking money

In year 2007 i was having salary account in abn amro bank and after some time i took one credit card. I used around 2-3 years and paid all the bills on time, one time it happens that i missed the payment and they put around rs-350/ penalty/interest etc.. I talked to there customer care and they take back that charge (I have the email copy) and i paid rest of the amount. After that i paid all the bills on time and after some time i called on there customer care ask for closure. They told me to pay the month due and cut the card and send to there head office after that they will close it. I did the same and they close the card. After 10 years when i am looking cibil score i found out the company me in black list. After so many calls i found the right person and send him the email communication which i already have with me. I send that 5-6 times in last 3-4 months but i did not get a single response from there side.
From last one week some recovery guys are calling and not behaving properly.
This is purely gunda gardi from the banks, can you please suggest the further actions which i can take as a responsible indian citizen.