I have had a couple of instances that receiving full payment on a couple jobs took some time. I try to not to get demanding. I approach the situation the way as if I were in their shoes. You say, isn't that hard? Yes, it is. But to have a heart on your shoulder instead of a block of wood or the whole tree, really takes Management. You have to ask yourself how would you like to be treated. You can be persistent, but also be kind and nice at the same time.  Be humble, you may not know the situation which caused the whole situation. Until you have walked a mile in their shoes you want understand. I received the best compliment in my whole business career from the company owner after it took 2 years for me to receive full payment of work completed. He told me, even though we have never met in person that he just knew I was a Christian due to the way I talked to him and my work ethics and the way I carried myself, and the way I treated him over the balance due.