Complaint sub-issue: Can't temporarily delay making payments

In XXXX/XX/XX/2020, Sallie Mae overcharged my account by over double my monthly payment. My monthly payment is just over {$610.00}. They charged me over {$1200.00} and they said it was due to a technical glitch. That set me back a lot as my checking account only had {$650.00} in it yet I was charged over {$1200.00}. My bank charged over {$100.00} in overdraft fees and my account was over - {$700.00} negative balance. My bank and Sallie Mae both said I had to contact the other to get the charge removed, which neither wanted to do. 

I only make $ XXXX/mo before tax. My bi-weekly paychecks are {$1400.00} before tax. With my account at over - {$700.00} negative balance, my paycheck was cut almost in half. Since this " technical error '' I have been struggling financially. 

Fast forward to today, I am furloughed, due to COVID affecting our business, until XX/XX/2020 and it looks like I will either be let go after that or I will only be working part-time at my current company. I have contacted Sallie Mae multiple times to see if I could get an extension on XXXX payment but they said no. They said they can not offer any assistance at all. 

Also, due to the technical error, as mentioned, I have been having financial struggles. Slowly I have been building back up by driving for XXXX for a few hours a day when I was working for my current employer and now for 12 hours a day so far since I have been furloughed but it is not enough to keep up with rent ( which I am also behind with ), car payments, insurance, etc.. 

On XX/XX/2020, I sent a payment of just over {$610.00}. The total amount due at that time was just over {$2400.00} and the past due amount was just over {$1800.00}. I sent in the payment of {$610.00} on XXXX XXXX and the balance stayed the same. I sent in, just recently, a total of {$650.00} to further catch up on my Sallie Mae student loans but my current balance is still the same. Past due amount is over {$1800.00} and total amount due is {$2400.00}. How is that possible if within the past 3 weeks I have sent over {$1200.00}! 

My past due amount should be between $ XXXX {$700.00} max and my total amount due should be $ XXXX {$1300.00} max. Why has my $ XXXX payments not been put towards this past due amount? I can not afford to pay the total balance Sallie Mae is saying I owe and again, in the past 3 weeks I have sent over 2 months worth of payments ( $ XXXX ) to catch up. 

I am not trying to get out of paying. Given my situation where I am not even working for my employer, I am just asking for two ( 2 ) things : 1. Please lower my total balance and past due amounts by the payments I have been making ( total is around {$1200.00} ). 

and 2. Please, if there is any way to get an extension for XXXX./XXXX so that my credit score doesn't get a bunch more late payments added, I would be forever grateful as this will help me refinance my car payment and thus help my ability to repay my student loans with Sallie Mae. 

As I mentioned, I am working as hard as I can to catch up on this but it seems that what I am sending isn't even reducing the total and past due amounts. Please help me out. I have called customer service and the seemingly 10s of account managers I have and no one is willing to help me out. My co-signers all have been affected financially by the COVID-19 pandemic. Getting constant calls and letters saying I am thousands of dollars behind when I literally just sent in over {$1200.00} is really worrying and stressful.