Mr. Cooper review: loan payoff

I had my mortgage loan paid off since June 2012, and have been contacting Nationstar for mortgage payoff documents. I was told that I owed for late fees and corporate charges. I continued to pay $1251.05 for months of June, July, August, September, October, November, December 2012, and January 2013. I continuously called to complain and to request papers explaining situation. I had received several different payoff amounts such as $4000, 2000, and 483. They continued to send documents to different address. I repeatedly attempted to correct address. In January 2013, I received check back from them in amount of $1251.05. I explained the check, was told not to cash check and to return by certified mail. I did. In February 2013, I received another check from them for the amount of $1251.05. I called and explained that I had received another check, And income tax statement with wrong address. The man I had been dealing with Devon Crowe had stopped taking my daily and weekly calls. He is consistently unavailable, will not return calls from his voice mail. It has been 9months and I am no closer to loan payoff documents. I have all the documentation and confirmation numbers. Can someone help me? The company won't answer their consumer e-mails and will not place me in contact with supervisor. Laura Haywood