Problem
A. Early in the letter, identify the reason you are writing-to register a complaint and to ask for some kind of compensation. Avoid leaping into the details of the problem in the first sentence.
B. Provide a fully detailed narrative or description of the problem. This is the "evidence."
C. State exactly what compensation you desire, either before or after the discussion of the problem or the reasons for granting the compensation. (It may be more tactful and less antagonizing to delay this statement in some cases.)
D. Explain why your request should be granted. Presenting the evidence is not enough; state the reasons why this evidence indicates your requested should be granted.
E. Suggest why it is in the recipient's best interest to grant your request; appeal to the recipient's sense of fairness or desire for continued business, but don't threaten. Find some way to view the problem as an honest mistake. Don't imply that the recipient deliberately committed the error or that the company has no concern for the customer. Toward the end of the letter, express confidence that the recipient will grant your request.