Nelnet Student Loan Complaint

Nelnet Student loan department,

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

I have been working hard towards keeping my credit in a good place and am currently trying to power pay on the Private Student Loan I have with the highest interest, while they ( the other - I have ) are in deferment. The last time I checked my credit score was about - and I contacted First Mark ( the private loan holder ) to see if I was able to refinance and they told me no. I just feel like 8 % is a lot for me to be paying in interest and was wondering if there is in fact a way to lower this loan so the extra payments I am paying will be worth it. Also, they told me that there is no way to put those extra payments ( After making the monthly payment ) directly towards the principle. I 'm also not sure how true this is either.