Formal Complaint:
* "I am writing to express my dissatisfaction with the service I received at your establishment."
* "I would like to lodge a formal complaint regarding the defective product I purchased."
* "I am filing a complaint about the unacceptable behavior of your staff."
Informal Complaint:
* "I'm not happy with how this was handled."
* "I've got a complaint about the noise coming from your apartment."
* "I'm really disappointed with the quality of this food."
More specific complaints:
* "I'm complaining about the broken chair in the waiting room."
* "I'm not happy with the way you treated my child."
* "I'm upset about the inaccurate information on your website."
You can also make a complaint by asking a question:
* "Can you explain why the delivery was so late?"
* "Why are there so many bugs in this hotel room?"
* "Is there something you can do about this problem?"
The tone and phrasing of your complaint will depend on the situation. Be clear and concise, and try to be respectful even if you're frustrated.