Product: Student loan

I have been working with Navient to pay off my student loans for several years. I set up a graduated repayment plan for my loans and track independently as well as on their website when the minimum amounts change. After my XXXX payment ( XXXX ) I noticed that my minimum payment for the next month ( XXXX ) went down by {$20.00}. I did not request a reduction, I had anticipated this amount going up as I entered the last few years of payments. Although I understand that I can overpay, if I had not caught this it would have extended the amount of time I was paying on this loan. I intend to pay it off by the end of this year, but this seemed an inappropriate change, especially because I did not request it and I did not approve it. 

In addition, recently my parents paid off loans for my brother. My father co-signed one loan with me but my parents do not and did not intent to make any payments on my loans. My parents arranged to pay off his loan with proceeds from selling their house ( yes they are selling their house to pay off student loans ). Navient was supposed to put all the funds towards my brothers loans so that those would be paid off. Instead they made a partial payment to his loan ( leaving a balance ) and then put money on my loan which was NOT something that was discussed or requested. After some time on the phone in a 3 way phone call with my self, my father and Navient, they said they would take the funds back, pay off my brother 's loan like they were supposed to and return to my parents and unused balance ( even though my parents sent in the amount they were told would cover the whole balance ). 

I have paid off 4 of my 8 student loans ( undergrad and graduate ), each time I paid off a loan I sent in the amount listed under the section on their website " Ready to pay off this loan today? '' This is where they list the amount you should send in if you are paying online or through the mail. I pay my loans exclusively online. I would send in the amount directed on their site for that specific loan only to have a small remaining balance after my payment cleared. Every final payment ( XX/XX/XXXX ; XX/XX/XXXX ; XX/XX/XXXX ; XX/XX/XXXX ) had to be sent in twice. Once for the amount they suggested and then again for a small amount, usually a couple of dollars $ XXXX, in addition because in the time I sent in the amount they suggested and when they chose to process and post my payment they would charge me additional interest. They know how long payments take to post, this is why they have a online vs. by mail suggestion for the final payment. This is a trick to collect more interest and avoid giving me the information I actually need to complete the final payment. 

I believe this same type of motivation was behind posting the payment to the wrong loan, to avoid the loan being paid off to collect more interest in between when we processed these payments, identified the errors and made the corrections. For the first example with my brother 's loan and my parents payment, they said it would take until the XXXX of XXXX ( original payment made XX/XX/XXXX ) to show the transactions had been fixed. I asked the customer service representative if they would be charging interest to my brother 's loan, knowing they are the reason it is not paid off and now needs to wait until the XXXX to be processed properly. The representative said he would make a " note '' that the payment should be back dated to try to avoid additional interest.