Firstly you must have a contract in place. This would be a written contract which you have both signed and dated etc. A court must have access to the original contract, not a photo copy. If there is a contract in place, then the person must have suffered losses to be able to claim money in the courts. He can’t just say you didn’t do the work, I want money. The builder must take all reasonable action to limit his losses, so he must be trying to find another plumber quickly to finish the work, he must also be able to demonstrate this to a court. If he does take you to court, there will be weeks and weeks of paperwork for him to go through, he must send you lots of letters and he must be prepared to accept less then he initially try’s to claim. If you are due money under the contract and he has failed to pay this money within a reasonable time frame then the contract has been breached, your defence will be that he breached the contract first, and you considered it is null and void, it would be wise to write to him asking for the money and offering to return to work once he has paid, sending the letter 1st class. He could end up owing you money in addition to what he already owes you. A court will understand that you go to work to get paid, if he doesn’t pay you then you wouldn’t go to work, this will be you limiting your losses for when you claim in the courts for the money you are owed (the judge will expect you to take some responsibility for your losses and trying to limit them), however if he was only going to pay at the end of the job and because you heard a whisper that he owes someone money and you started to demand it now and he has offered to pay some and you refused to take it then your likely to fail, but I would be amazed if he really would take you to court. If a person gives a cheque, knowing that it will “bounce” then he has committed fraud, this is a “criminal wrong” not that the police will do much about it as with little investigation a presumed defence would be that it was a mistake and therefore the police won’t waste their time. Now if what really happened was that the builder came on site and had a go at you, put you in fear of violence and told you to go away and not to come back then I can’t see how he could make a successful claim in the courts.