Seller, agent renege on home repairs

DEAR BARRY: We purchased our home about a year ago. The sellers and their Realtor made a side agreement to repair some of the defects after the close of escrow. These included a new liner in the chimney, a new exhaust vent for the furnace, and a vent for the clothes dryer. The repairs were supposed to be done within three months of closing, but the sellers still have not completed the work. The person they sent to do the work is unlicensed, has no insurance, and won't give us his last name. He hasn't gotten a permit for the work that he has done, and what he has done does not look good. The new clothes dryer vent is plastic flex pipe that blows into the attic. The seller now says that the chimney does not need a new liner and has declared that all of the work "is done." To top things off, the Realtor won't return our calls. Instead, her attorney has called us and has rudely warned us to stop calling the Realtor. What in the world can we do? --Leslie DEAR LESLIE:...