Hi.
I graduated last May, and have a full-time job making six-figures.
Monthly loan payments have not been a problem as I have consolidated with SOFI for most of my loans. What I was not aware of, was that I had a loan with FedLoan Servicing (https://myfedloan.org/). I didn't receive any kind of communications for repayment of my loan, and as such, the payments (started in January 2016) became delinquent. I have since paid the delinquent payments and set up auto-debit, but I still have some questions. The delinquent payments were clearly submitted to the credit bureaus as I noticed a 175 credit score drop last month (from Bank of America's monthly report tool). I looked into the FedLoan Servicing online tool, and they allegedly only sent out oneletter for a late payment. It never arrived at my address...
Is there anything I can do to resolve? I am concerned that these four payments becoming delinquent will tarnish my report for the next 7 years, even though I have the ability to pay the monthly balances. I asked on Reddit, and someone suggested sending a goodwill letter stating that I received no communication from them and had no idea they were going to be late. I would assume an apologetic-esque approach would probably be best?
I have since added auto-debit/auto-pay to the system.
I also just signed up for CreditKarma, and I see the delinquent payments in my report 
I have a total of 175 payments according to CK, with an on-time payment rate of 94.2%.