I would contact the disability office (sorry for my typo earlier). Ask for an advocate to help you work with the student loan department. I do think you would get one person assigned to you in that case.

It's also entirely reasonable, as someone else suggested, to demand that all of this be done via email in order to generate a paper trail -- which you really need if this office is retaliatory.

You also have the right to ask for a supervisor if Mr. S picks up the phone.