Citi Bank Student Loans Giving me Problems i think i need a lawyer?

I am having a problem with Citi Bank student Loans. I have been behind on my loans and they tell me that the loan defaults at 120 days so every month for the last year i have been calling on the 20th of every month and paying the minimum payments to keep the loans 30 days back and twice already now three times counting this one they have either misapplied the payment or not charged the correct amount and each time they require more money as if i was at fault and now this time they want me to sign up for recurring payments and send a letter saying that i want them to bring the loan back. Is it legal that if i made the payment that they said was enough to bring the loan 30 days back ($61) and in reality the payment should of been more ($67) that they put criterias and threaten me that they will leave the loan charged off if i do not sign up for 6 months of recurring payments? as if i did something wrong. I stayed within the minimum payment and the loan has never been charged off because of me but because of their stupid mistakes. Please help i cant take this anymore what are my rights.