Complaint Review: Green Tree Servicing

I have an equity line of credit with Green Tree.  It was originally with Irwin Home Equity, but several years ago, they went out of business and Green Tree took over my loan.  I have always paid this loan, which btw, has an extremely high interest rate and also has a balance that seems to go up with each payment rather than down.  On possibly two occassions, I have been five days late in paying, which actually falls within their so-called "10 day grace period."  During those five days, I have been harassed by the company, who call literally every 1/2 hour, all day.  As bad as this is, it has now gotten much worse. 

I am currently in the process of obtaining another loan through a different company who will pay off my equity loan through Green Tree and provide me with a much better interest rate.  My loan is ready to close, all but one factor...Green Tree.  The company has attempted to get a payoff amount from Green Tree for the past month and 1/2.  Green Tree refused to give it to them.  The issue is that they do not have access to the original contract that was made between myself and Irwin Home Equity in 2006.  Apparently, Green Tree took over the loan when Irwin Home Equity closed, but failed to keep any records...so they say!  There records, as I am told by representatives from Green Tree, are kept in a "vault."  And it seems that no one can access this vault.  My original contract with Irwin Home Equity said that if I prepay the principal on my loan before the first five years, then I am required to pay a penalty for early closure.  The fee is based on six months of interest for the amount being paid off or $500, whichever is greater.  I have no problem paying this, but Green Tree says they do not have a copy of this part of the contract because it was an addendum that is now tucked away in this mysterious vault.  And according to them, they can't get to it and have no idea when they will be able to.  So, they aren't able to provide the company I am trying to refinance through, or myself a payoff amount so that I can pay off the loan in full.  I have faxed in my copy of the original contract with Irwin Home Equity, which expressly defines the penalty, but they will not accept it.  They also will not allow me to pay off the principal without the penalty fee, even though they have no record of this part of the contract.  Sounds to me as if they are stalling and/or not doing their job on purpose, so as to prevent me from obtaining another loan and paying off this loan, and therefore losing the astronomical amount of profit they would otherwise continue to receive from me for years and years to come.  I have called and called, and am told there are no supervisors or any other numbers, departments, or anything to contact.  I can sent in a dispute letter, but that is the only option I am given.  Apparently they don't want anyone to payoff their debts...