It's easier said than done, it's better to curtail such behavior from the client from the beginning. Some businesses make it easier for owners to curtail such activity, for instance, as a fashion designer, my clients pay an instalment for their clothes because l tell them that l need cash to buy the sewing materials l need to make their clothes, and once l am done with their clothes, they will pay up the balance to collect their clothes. Failure to do so means that your clothes will remain with me.