This fillable complaint letter provides sample information that can be replaced between the brackets.
Dear {Name},
On {date}, I {purchased your product/attended your event/visited your establishment} at {location/website}. According to {the invitation/your website/a representative}, {policy}. Therefore, I was under the impression that {outline expectation here}.
{Detailed description of what went wrong. If the product broke, describe how. If someone was rude or unhelpful, include their name and the unsatisfactory behavior. If you feel you were led astray, explain what you were led to believe.}
I have always been {patient/a loyal patron/etc.} but I was extremely disappointed in my experience on {date}. I would like to request that {my product be replaced/the employee be officially sanctioned/you change your policy, etc.}. I also believe that I am entitled to {a refund/compensation} in the amount of {amount}.
Thank you in advance for your understanding and for your quick response to this situation.
Sincerely,