"In my current role, we have processes and procedures in place to handle this type of scenario. In my case, I will call the customer directly and be casual about it, on the first call. In all my years of working, I have only had this happened a handful of times, and typically there is a logical explanation like the customer had a check bounce from someone, used the wrong check from a closed account, or their credit card expired, and they were unaware. When you are friendly with customers, they will always find a way to repair the situation as soon as possible."