File an Online Complaint. You can file a complaint about a business in New York City that fails to deliver goods or services.Report non-delivery of goods or services from a: Hey, so if you ever have a situation where your mail or package marked as "delivered" goes missing due to theft, you can file a claim with USPS. To file a formal complaint, you must put your complaint in writing and sign it. Your attorney, if one represents you, may sign it instead. Learn about the requirements for preparing and filing a civil complaint, including how to prepare a summons, along with some cautions. Your documents must be served within 120 days after you file the complaint. The Post Office has exclusive access to letter boxes marked "U. Click to visit Basics of Court Forms and Filing for specific information about how to fill out forms and file in the district and justice court.