What consumer laws make contracts enforcable? -

A contract is written to outline what work will be done and for what price.The day the contractor arrives, the customer walks throught the project to make sure there is no misunderstanding of what is to be done.The contractor feels the customer has money so he decides to do extra work to make a bigger profit.What prevents a contractor from doing what he wants and demanding more money for it?After the customer has paid the agreed amount in full, what can the customer do to stop the harassing phone calls demanding more money and threats to come back and undo the work?

The answer will vary from state to state. You need to see an attorney in your state to get an answer specific to your situation. Without knowing what state you are in, I do not know if I am licensed to practice there so this is NOT legal advise, just a general answer to a question about contract law. You mentioned a contractor so the work may involve work on land (real property). That could involve something called the statute of frauds (which has nothing to do with fraud) which says that a contract must be in writing to be enforced generally. There are exceptions but if you did not get a written contract for the additional work he claims he did, he could be out of luck. Again, talk to a lawyer in your state to be sure. Since you did not mention getting a written contract to begin with though, I am concerned you may not have a written contract. In that instance, it is your word against his and up to a judge or jury to decide what the real agreement was. There is no need to waste time argung or debating with him on the phone and it will only frustrate you. If you do not want to pay him, tell him you do not intend to pay and suggest that he file a suit if he wishes and you can both discuss it in court. You feel he is trying to take advantage of you and did unauthorized or unnecessary work. He feels you are trying to avoid paying for necessary work. Those are not easy positions to reconcile and that is what the court system is for. There are alternatives like mediation, arbitration and such but the absolute worst thing you can do is continue to be troubled about it or continue to engage in arguments. That is not helpful for either of you. Depending on your state, he cannot come back and undo the work in most states I know about. As for stoppping him from calling, nothing will do that unless he is truly harassing and then you need to report it to the police. But from experience I can tell you that those types of action will probably egg him on more than if you just ignore him, hang up on him or otherwise do not engage with him. The argument that he is harassing you by telephone will open a whole new can of worms and involve a lot more people and none of it will be a good thing. The contractor wants drama and wants to annoy you so filing a complaint with the police will just feed his ego most of the time. Ignore him and tell him to take it to court and you can both discuss it there.