A formal Letter of Complaint is used when dealing with a problem situation that is not being amended through other measures of communication (i.e. phone calls or emails). The Complaint Letter formalizes a situation into official writing and is normally written as a last resort. Your Complaint Letter should be concise, factual, and authoritative while remaining constructive and friendly in order to encourage action and receive a positive response from the reader. Use our templates as a reference to write your own or fill out the letters as needed.