Reversing a charge for 2nd home owners insurance policy

There is a $2,000 charge added to my loan payoff balance for an insurance policy imposed by Washington Mutual.I have been trying to work with Greentree since May of this year. I have provided proof of continous coverage from day 1 of this loan to the present. It appears as though Greentree is giving me the run around. I really need to sell and this extra ammount is not helping. Any help out there? Chuck