Need Legal Advice for Foreign Resident Rights (Tokyo)

So before I showed up in Japan I did my research on ALT (assistant language teacher) recruiting companies and apparently (despite research) have landed myself with a very difficult to work with company. They have placed me in a very remote area of a very large city with no transportation. They will not help me find a car to rent, so I have found someone willing to rent to me. The problem is, to get Japanese Auto Insurance (and the car) I need a letter from the recruiting company to prove that I am an employee. They have yet to respond to the e-mail I sent almost a week ago requesting a proof of work letter.

Now, I know that Japanese people don't like confrontation, but I am ready to throw in the towel and hand them my resignation letter. They have been incredibly unfair to me and to not even respond to such an e-mail throws up a big red flag for me. They have placed me in a very difficult situation and the recruiting company doesn't care about how I'm adjusting. I have been sick many times since I've been here and I am at a point where I am ready to head home if I can't get help. Does anyone know of anyone I can get in touch with in Japan that can help give me legal advice for foreign resident rights?