complaint letter against a therapist

Due to a single incident of unprofessional conduct, I am seeking to file a complaint against my therapist. I have documented evidence that can be used to support the complaint. I am looking for assistance in composing a complaint letter so that I can get justice. The letter must be professional, appropriate, and effective in presenting my case. I need to make sure that it represents my views and interests. The letter should clearly explain the incident and its consequences for me in order to support the complaint.