回复：毁约的后果

Do you have a written consent when both of you agreed to use the big size window with the trim free to you? Do you have the original contract that indicated the size of the window you desired to have. If you do, just threaten him you will sue him in a small court of breach of contract and the damage of the house. Even if you don't have the written document, you still have a good case to win. Write down the factual detail of the whole story, then talk to the owner to see if he will yield or not. Otherwise, sue him.