Kotak Mahindra Bank — Closure of credit card

I have created a salary account with kotak mahindra bank without knowing to me they have issues credit card and that is also not reached to me. Even though they have charges me 590 rs as credit card maintenance.so I went to kotak Hyderabad Madhapur branch and explained the issue and asked and given letter for account closure.But they have not closed my account.Again I visited nellore branch kotak bank and asked for closure. This time the account is closed.i have paid all due balance include credit card maintenance.This complete process is completed 3 yrs before.But still the credit card balance is showing negative in my cibil score.So for this the kotak cs team is asking for my bank statement.
How can I provide bank statement for closed account?
The Cs team is sending standard computer messages and they are not even trying to resolve my issues.

Please dont go with kotak mahindra bank.it is worst bank ever to resolve customer issues.