Name (Mention the name of the recipient)
Designation (Mention his designation, if applicable)
Company (Mention the name of the company to which he/ she belongs, if applicable)
Address (Mention the complete address of the recipient or the address of the company he belongs to, whichever is applicable)
Date (Write down the date on which this letter is being sent)
Subject: Write down the purpose of writing the letter in one line
Dear Mr. /Ms. /Mrs. Last Name
First Paragraph: Give warning to the recipient and state the reason for the same.
Second Paragraph: Write some details of the incident and tell them that this kind of behavior was not expected out of them.
Third Paragraph: Warn them once again and ask them not to repeat such a mistake.
Thanks and Regards,
Name (Mention the name of the person writing the letter)
Designation (Mention the designation of the person writing the letter, if applicable)
Name of the Organization (if applicable)