Can anybody please help me?

Starting at the beginning; I had a card that became past due, I contacted them, they gave me 30 days to make a minimum payment, i needed to give a good faith payment to keep it from collections and made a large payment, when i called to secure what was left they notified me that they charged it off and refused to take the payment, later receiving a letter that it had been charged off three days after they received the payment. The CA refused to make a settlement and though I put every penny into the debt more than half goes to interest every month. The CA representative said I'd only have interest applied annually...I've tried everything online i have seen and was told I could ask for Hardship via the FDCPA but can't find anything. Could someone please point me in the right direction?