Product: Student loan

I have had issues with Navient ever since I started making payments XX/XX/XXXX or XX/XX/XXXX. Navient constantly harassed my father and I with phone calls whenever I got behind. Navient refused to remove my father as a cosigner after I completed the necessary requirements of XXXX consecutive payments saying my payments were late even though the payments were set up by Navient to automatically draft from my account. I asked Navient on multiple occasions to consolidate my loans and lower my interest rate but they refused. Navient would only offer to put me in an income based repayment plan to lower my payment but all it would do was extend my number of payments. 
The most frustrating concern was their lack of communication. Every time that I would call to either get clarification on my loans or make a payment, they would not have any records of my previous calls and I would get cold transferred around to multiple agents to the point that I would just make a payment just to be done with it. 
My biggest complaint is that I was led to believe that, XX/XX/XXXX, I would finally be able to consolidate my loans to a fixed interest rate of 3 % on all my loans for the remainder of my repayment period. I set up another XXXX consecutive payments through Navient to be automatically withdrawn from my bank account. I upheld my responsibility to have each payment clear my account until I received a phone call from my father stating that Navient called and told my father that I was behind on my payments. Upon learning this information, I reached out to Navient to obtain an explanation. They fraudulently changed my interest rates back to their original amounts after I agreed to a verbal contract to pay the 3 % until the end of my repayment period. I refused to pay the higher interest rates. In addition, I requested on numerous occasions to have a physical copy of the recorded telephone call and/or telephone call transcript sent to me. Navient refused to provide that information unless I had legal representation request it. My account became further and further delinquent and finally defaulted about 3 months ago. 
About a month or so before I defaulted, I obtained legal representation ( around XX/XX/XXXX ) regarding the issue. We attempted to work with Navient to discuss options but to no avail. All that I was trying to accomplish was to get my rates lowered backed down to 3 % to honor our previous verbal contract and continue my repayment payment. Every time my lawyer and I would call in, they had no record of our previous communications. I was left threatening voice messages by Navient during this time. On the last day before my loan defaulted, I tried to call and make a payment to keep that from happening. Navient claimed that the department handling my account closed down at XXXX that day due to it being the last day of the month and the main customer service number refused to take my payment leading to my default. 
Since defaulting on my loan approximately 3.5 months ago, neither my legal representation nor I have received any communication from the debt collector regarding the default. We have contacted Navient on multiple occasions and they do not even know where my file is and can not give me any information on who to contact to track it down. 
I am beyond frustrated. I read the article regarding the lawsuit today and did not realize that I had someone who I could complain to. Any help would be much appreciated.