I need help. I have an $18k balance with Citibank. No, it's not irresponsibility, they gave me a fixed 3.9% for life rate and I transferred the balance of my truck to it. I've saved a ton of money on interest. Two months ago I made a payment online. Something happened, either I forgot to put the last digit in the account number on, or their system truncated it. I was given a confirmation number and told "payment accepted". A month later (last month) I received a statement saying my payment had NOT been accepted due to the last digit missing from my account number, and they had increased my interest rate to 28%, and charged me $400+ in interest and hundreds of dollars in fees. I called them on 5/28. They told me that they had credited all of the fees and fixed my interest rate back to 3.9%. I made a double-payment on the account to catch up for the previous month. Yesterday I got my bill. They hadn't fixed the interest. Now I have another $450 in interest charged to the account. I should have a total of about $50 in interest, but I've got over $850 now!! I just talked to a supervisor. She fixed my interest rate back to 3.9% but is REFUSING to credit the $850+. What do I do?!?! I sat here and argued with her on the phone but she won't give me my money back. Here's my line of thinking: 1. I have a perfect credit rating. Absolutely perfect. 2. I refuse to pay the $850. This is extortion, and bullshit. She said "Well you put the account number in wrong." I said "OK, let's assume I did. I'll pay the first $400 you charged me for my supposed fault. You then can credit me the other $450 because your agent screwed up." She refused. 3. I've been told if I don't pay the $850 they will keep charging me interest based on that and will, eventually, send it to collections. So they're going to totally trash my credit rating if I don't pay their extortion fee. If they're going to ruin it anyway, hell, I might as well stiff them for the entire $18k. Either way, my perfect credit is ruined. I told her this and she said "Making threats against the account isn't going to help you." Well, screw them. Look, I have more than enough money to pay this. It isn't about that. It's about what is right and wrong, and what they are doing to me is wrong. What happens if I just stop making payments? What happens when collections starts calling? What can they do to me? Note that this is UNSECURED debt. They can't come take my belongings over it, can they? Can they sue me? What happens if I declare bankruptcy? Obviously I'm not bankrupt, but I'd be willing to do it to stick it to those asshats. I am more than capable of paying cash for everything for the next 7 years. Yes, I owe them the $18k and I know I should pay it. Up until now I never intended not to. But right now this is the only bargaining chip I have in this battle. How can I use it against them? All I want is the last two month's worth of back interest @ 28% reduced back to my normal rate of 3.9%. But if they're going to sue me and attack me and destroy my credit instead, then I might as well get something out of the deal. I figure I'm willing to trade ruined credit for not having to pay any of that debt. I mean, you know, if they're going to do it to me anyway. Please advise.