SBI Credit Card — Payment excess

Address: Gautam Buddh Nagar, Uttar Pradesh, 201301

Website: state bank credit card

I had a credit card of sbi. The payment was setteled at 70000/- and in 6 months. Paid 55000/- timely to their persons. After that no body turned up for two months. Then after 2 months person came asked for a minimum payment of 3000/-. This process continued for 6 months with promise that now only 1200/- is pending. I told them to give full and final letter and take money. They are denying and again asking for the whole payment. They are saying you are defaulted. What is the option to fight?