When I got the loan they gave me an address to send the first payment and a different address to send the second payment.
I sent in each of these and they were credited fine.
Then they sent me additional changes of address and I didn't look closely, assuming these were duplicate of the first change of address.
When I sent my 3rd payment, they returned it marked "Received" but indicated that I had to send it to a different address and it wasn't credited.
After resending the payment (but before it was received), they charged me a late fee, even though they marked my payment as received.
They did call me a couple of times but never left a message saying I needed to mail to a different address. When I returned their call, I couldn't get through because they said I entered the wrong last four digits of my SSN (of course the problem is theirs, not mine, I know my SSN).
When I called them, they said it all must be my fault and I have to pay the late fee and if I don't hurry up they will ding my credit.