Navient Solutions, Inc. Student Loan Complaint

Navient Solutions, Inc. Student loan department,

Non-federal student loan Dealing with my lender or servicer Trouble with how payments are handled Massachusetts

I took out a private student loan in - with - -. The loan was sold to Navient in -/-/-. My interest rate is 12 %. I have been consistently overcharge every month and some moth - percent of my payment is applied to the loan. My original loan balance was $10000.00 in -/-/-. My balance as of today is $8600.00. Navient can not explain how my monthly interest, principal and fee are being applied. Some months there is absolutely no money is being applied to the principal at all. I am trying to refinance the loan with them and they will not do so. I have good credit so I will try elsewhere.