Product: Student loan

Hi, I had a payment due on my Navient Student loan on XXXX XXXX, 2015 for {$180.00}. I called in on XXXX XXXX, 2015 to make the payment, I was informed that because i was using my debt card i would be charged a {$15.00} fee, which completely blew my mind. Being charged a {$15.00} fee to make a payment using my debt card is XXXX % robbery. I felt as though i was being strong armed because i needed to make a payment so i would n't be late but i only have a prepaid debt card. {$15.00} may not seem like alot to most people, but an extra XXXX $ is the difference between being able to eat dinner for two night or being hungry. I live on my own, I do n't recieve any help and i do not make a lot of money and it embarrassing to say but I 'm barley getting by so naturally i was fustrated and Ill admit i copped a little attitude but nothing bad like cursing or yelling just gave straight answer with out any thank yous. STILL, i made the payment. 
Now fast forward to XXXX XXXX, 2015. I signed into my account on the Navient website to check when my next payment was due. To my surprise, I have a past due balance of XXXX on my private loan. Confused, I then look at my debt card transaction history and see the payment i made for XXXX ( XXXX ) was taken out by Navient . The following day, after getting home from work I call there customer service department ( around XXXX ). I begin speaking with a representative and explain the situation. She informs me that representative who took the payment applied it to anther loan I have with them. Keep in mind, they record the phone conversations and I am 150 % positive I made clear the payment was for my private loan. Moreover, the only payment due was the XXXX on my Private loan. My other XXXX department of education loans did not have a payment due until XXXX XXXX, 2015 and the payments for the loans are not XXXX. So i came to the conclusion the previous representative was angry with me and most likely did it not purpose, but that would be difficult to prove. Nevertheless, I asked the representative so what happens now. She informed me that she could only make a request to have the payment reallocated to my private loan which would take 10 days. Frustrated, but still being polite i explain there has to be something else that can be done because if it takes that long my loan would be past due 22 days and after 15 days of being past due, it is reported to the credit bureau and why should my credit be negative effected for a mistake that your company made. This immediately has an attitude and responds by saying, " well then you 'll have to make a claim on our website and once we review it and see that it was our mistake we will withdraw the report ''. I then asked, why I have to go through that entire process, for a mistake that you guys made? How does that make any sense? You guys can charge me a XXXX fee to make a payment using my debt card, you can completely harass my family with phone calls and destroy my credit and thus my life if Im late making a payment, but if you guys make a mistake, there is absolutely no repercussions for you and on top of all that I 'm supposed to fix it. She responded by saying my apologies sir can you please hold. Places me on hold for an hour. I hand up the phone call back and have to explain the entire sistuation again and she puts the request in and tells me the same thing the previous representive said as far as my credit.