At one place you have mentioned that there was arrangement of auto debit of full amount of the bill and at another place you have mentioned minimum amount was transferred. It is felt that some amount was left unpaid and this has compounded to become big amount. The CC company might have sold the outstanding and collection rights to this recovery agency.
The best approach is customer should write to the CC company that he wants to close the CC and ask the company to supply the final bill and ask the local office to confirm the receipt of final payment and that card has been destroyed in their presence and then to obtain NOC.
You are within your rights to get the statement from the month some balance was left unpaid in your CC account and each subsequent month to the current month depicting balance for each month and penalties, finance charges, interest, late payment charges levied.
The CC company plays trick that a/c has been closed and thus avoid to supply detailed statement and press for final amount without providing any details.
You may ask the agent to supply you thru redg post, a detailed letter along with statement for each month enabling you to revert properly. You may record the conversation.
You have the option of writing to the CC Company also. You can choose to enter into settlement however in this case the CC Company may update the status of balance amount in its books as written off which shall be read as default. Therefore you may obtain a prior written confirmation that settlement shall not affect your credit history and loan taking ability adversely, and company shall clean your credit history and withdraw your name from all collection/recovery agency, credit bureau’s, MCNF ( Master card negative feedback). You may take the help from a lawyer experienced in CC matters.