Standard Chartered Credit Cards — Unreasonable late/finance charges

I have spoken to bank representative to cancel the card and to clear all balances on the card more than a year back. After clear communication from the bank I paid the remaining balance (INR 400) with the understanding that this would clear my accounts.

However, now the bank says I did not pay the amount in full and the total balance now due is around INR 4, 000. They are saying that I should have asked for the "full and final settlement" letter from the bank, but my argument is that they did not mentione about any such requirement at the time of the settlement.

My history with the bank is that I have cleared all the purchases made on the card in a timely manner ever since I have been their customer. And I have put my best effort to close the account with the bank by talking to their representative. However, I think, the bank is unreasonably asking me to pay such high amount for no fault on my part.

Please help me resolve this conflict with the bank.

Regards,
Archana.