How To Write A Complaint Letter About Workplace Bullying . If you think your conflict with a coworker is something you can resolve together, then consider attempting to write a letter to your boss. Make a complaint to the relevant workplace health and safety authority. Employee Harassment Complaint Letter Sample Collection Letter from simpleartifact.com It should be written in formal business style and a copy should be kept in the event that any legal action needs to be taken at a later date. A complaint letter to hr is an important step in documenting a serious workplace issue. For example, you should state that you want to lodge a complaint about harassment and identify your harasser.