How do you write a letter of complaint following the rules for a business letter and using the full-block style?

To write a letter of complaint in full-block style, start with your address and the date at the top, followed by the recipient's address. Use a formal salutation, such as "Dear [Recipient's Name]," then clearly state your complaint in the opening paragraph, providing specific details and any relevant facts. Conclude with a polite closing statement, such as "Sincerely," followed by your signature and printed name. Ensure that all lines are left-aligned, and avoid indentations to maintain the full-block format.