Auto Loan Charge Off

My question involves a consumer law issue in the State of: South Carolina. I have an Auto loan through Go financial. 2 years ago while I was in graduate school I fell behind on payments and my car was repossessed. In the process of making a large payment and redeeming my vehicle I found out it had been charged off 3 months before but I was not informed. I was told, verbally mind you, that I now had only a ten day Grace period before my car would be repossessed. Fast forward to last month. I have been making monthly payments on time or within the ten day window since the charge off. I knew my loan was getting closed to being paid off and asked for a payoff quote. I was told it was 500.00 more than what I believed it to be. I requested a transaction history and it was provided. The balance on my transaction on my transaction history says $1224.00 but the payoff quote is $1778.00. When I called to speak with someone I was told the additional amount was interest and fees from before the loan was charged off. It does not make sense to me because my transaction history shows everything (pre and post charge off) and I do not see where this extra 550 bucks is coming from. Then the lady told me I have no Grace period. My current payment was due on August 28 and I told her I would be making it on Friday, Sept 1. She told me this was unnacceptable, their was no Grace period and a payment had to be received each month so I only had until Thursday, August 31 to make the payment or it would be put out for repossession on Friday. This company has been extremely rude and predatory to me even though I have made every effort to continue paying this loan. I am extremely frustrated and wondering what is to keep them from adding on additional fees/interest so I am never able to pay it off. I am also afraid I will get the balance down to $100.00 and they will come repossess it because according to the lady they can come get it at any time since it is in charge off status. I would like to know if they can add on that extra 550.00 even though their transaction history sheet only shows my balance as 1224.00, not 1778 and what rights do I have as a consumer when my auto loan is in charge off?

Auto Loan Charge Off