Sallie Mae ruined my credit today

I am a moderator over on a self help credit repair forum, so I'm pretty in tune with credit reporting and how it works and what not.

Imagine my surprise when I find out that Sallie Mae has recently modified their accounts as they appear on my credit report to make it seem as if I'm only paying part of my monthly loan commitments - it drops my score from 665 to 558 - over one hundred points!!

I am in repayment, have been for over a year, never made any late payments or partial payments, but "somehow" there is a notation at the end of each student loan entry on my reports that states "Arrangements made with credit grantor to make partial payments"...can I call BS on that? I'm going to on Monday.

Anything I can do that I'm not thinking of at this point - I admit I am very emotional right now. I have a draft of a BBB complaint that I'm sending out on Monday (depending on the answer I get form the phone drone when i call), as well as drafing a letter to the highest person at Salliemae I can find. What am I missing?