You are right devowriter. It's not easy. There are times you would have to balance with your own money when you run into shortages. No one is ready to listen to stories. And when you have overage, you can never take it for yourself. You must declare it in your account if peradvenyure, the error was due to overpayment from the customer. But, when you are very careful with your work and pay attention to every detail, you have less issues.