Product: Student loan

Hello. I have a formal complaint to lodge against Navient and am trying to go through the proper channels to do it. 
Here is what occurred : I wanted to send in a bulk payment of {$2000.00} in XX/XX/XXXX since some unexpected money had come in ( my aunt had passed away, and a small bank account was located with a couple thousand dollars ). 
I called Navient BEFORE I sent in the XXXX to get their assurance that the money would be applied toward my monthly payments ( which were {$110.00} at that time ) and not toward the principal. We discussed the time that payments would resume in XXXX or XXXX of XXXX. 
I received their guarantee that this money would be applied to these monthly payments which would have meant that another payment at that XXXX rate would not be due for a year and four months ( so around XX/XX/XXXX ). 
I sent in the payment of {$2000.00} on XX/XX/XXXX. 
I was asked to fill out the income-based paperwork in XXXX or XXXX of XXXX, and I submitted it. I made less that year than the previous year. 
I received notification from Navient that I would need to start making payments of {$55.00} in XX/XX/XXXX. 
I called Navient in XXXX and an hour and a half into the inquiry, the supervisor agreed with me that no payment was due until XX/XX/XXXX, in fact if the payments were calculated starting in XX/XX/XXXX at XXXX, the payment already sent in should be applied even past XX/XX/XXXX. The supervisor who confirmed that what I was saying was accurate stated that he would send a confirmation of the adjustment within ten days. 
The adjustment confirmation did not arrive. 
I called back and was given some story about the previous year 's payment schedule having ended after 10 months instead of the full year ( no explanation given concerning why that would have been true, especially since I always turn everything in on time and properly completed & no payment schedule before this one had been ended early ) and that my payments had reverted back to the originally threatened $ 300+ that would 've been the amount due if I had not applied for income-based consideration. 
Since they cited this 300+ amount as what was taken out as payment from the {$2000.00}, they had come up with monthly payments of {$55.00} being due starting in XX/XX/XXXX. 
I have not had time to say anything about this due to my mother 's sudden illness and consequent move from the house where she 'd lived for 28 years. That plus my job have kept me over-occupied until now. 
The bottom line here is that Navient lied to me at all points along the way and stole portions of my money that they were not entitled to. 
I 've been making the XXXX payments since XX/XX/XXXX since I have no recourse. 
I contacted the Navient advocacy group, and it turns out that the income-based program that I was in when I called them in XX/XX/XXXX has particular perameters that would have precluded the payments being applied past a year. They readily agreed that I was given misinformation but that they did not have the power to go back and adjust anything ; all they were willing to do was to pass on the complaint. 
It is my contention that Navient still is responsible for what I was told. They dispensed the misinformation upon which I based my decision about where best to distribute the money. I was trying to be responsible and have the payments covered almost up to when I retire in XX/XX/XXXX. I would have put the money toward paying off my credit card or toward the principal on my mortgage otherwise. They can not give people misinformation that people act on in good faith without being accountable. They ca n't tell people the wrong thing that results in loss of money on the consumer end and then just say sorry, sorry. 

Sincerely, XXXX