School's Admissions office ignoring me after accepting admission offer So I'm in a bit of a weird situation right now.

I recently graduated from university with my BS, but was expecting to continue my education at the school as I was accepted into a BS/MS program at the end of my junior year. I put a tremendous amount of time and effort into my work and knocked out a significant portion of my MS during my senior year. 

Since I graduated I had to do some transitioning into the MS program, which consisted of proving that I actually had my degree conferred, filling out some additional paper work -- you get the idea. I filled out every form that needed to be completed, met every deadline, and so on (and have tangible proof/records of me doing so). 

And yet for some reason, I'm still not in the graduate program (The offer was never rescinded or anything like that). Even though I've done all of the work I've needed to do and was already accepted, I'm simply not considered to be in the program for some reason and can't register for classes, receive financial aid, etc.

I tried desperately to solve this matter with the graduate admissions office via e-mail, phone, and in-person meetings, and yet I've been continually left without help and without answers every single time. Class registration + Financial Aid deadlines are coming up and yet it looks like I'm posed to miss them due to the admission office's neglegence towards this matter (And mind you, this is not some kind of fake/phony/fraudulent school. This is a very well-known, reputable university in the US)

It's honestly gotten to the point where I'm preparing a letter to send to the president of the school, as I've run out of people to go to for help. It's been really frustrating to have done all of this work for so long and then be treated like this, and I don't know what do to.

I'm not really sure what to ask at this point, but absolutely any help/recommendations would be sincerely appreciated. Are there any actions/repurcussions I can possibly take against the school for this? Or are there any other courses of action I should take to help resolve this matter?

Thank you.
There should be faculty members in the department you are to be enrolled in who are responsible for graduate student admissions and advising. These people should be able to tell you what's going on with respect to your case because, unlike undergraduate admissions, graduate admissions decisions in the US are made with the consultation of faculty members and not simply by a "central" graduate admissions office, which usually just acts as a clearinghouse for the applications.