Great Lakes Student Loan Complaint

Great Lakes Student loan department,

Non-federal student loan Dealing with my lender or servicer Washington

I have been making my payments via automatic deposit. I have set it up so that I pay more than what is due. I recently noticed that my account said that my next payment is not due for another - months. I had intended the extra money per month to go towards the principle of the loan. I called Great Lakes and asked them to do this. The customer service lady gave me the run around and eventually told me she could not do that. However, Great lakes website says that I CAN in fact do that and that there is no penalty in doing so. They are charging me interest daily and I tried to explain that I did not want to get charged daily interest on a principle that I was trying to pay down.