My husband and I sold a house to a couple 3 years ago on a land contract. They paid $5,000 down and agreed to make a monthly payment. They a

My husband and I sold a house to a couple 3 years ago on a land contract. They paid $5,000 down and agreed to make a monthly payment. They also agreed to assumed the property taxes and insurance responsibilities. In the contract it stipulates that they will keep the maintenance up on the home and pay the refuge and municipal fees. We just found out that they have vacated the house and have hired an realator to sell the house. Also they are over three years behind on their refuge (trash) bill. The house is in horrible condition. We live out of state and have just seen it. What are our legal options