Do not delay and do not apologize. Complain as soon as you realize a mistake has been made; delay not only weakens your case, but can complicate the matter as the people you are dealing with might forget the details. And there is no need to open your letter by apologizing for the need to complain (We regret to inform you, I am sorry to have to write to you about); this also weakens your case. Begin simply:
We would like to inform
Do not be rude or personal. In most cases correspondence between firms takes place between employees in various departments. Nothing is gained be being rude to the individual you are writing to; you may antagonize someone who has probably had nothing to do with the error and, rather than getting the error corrected, she/he could become defensive and awkward to deal with. Therefore, do not use sentences like:
You must correct your mistake as soon as possible.
You made an error on the statement.
Use the passive and impersonal structures:
The mistake must be corrected as soon as possible.
There appears to be an error on the statement.
Do not use words like fault (your fault, our fault) or blame (you are to blame); these expressions are not only rude, but childish. Therefore, do not write: It is not our fault, it is probably the fault of your dispatch department.
But: The mistake could not have originated here, and must be connected with the dispatch of the goods.
Terms like disgusted, infuriated, enraged, amazed have no place in business. You can express dissatisfaction by saying:
This is the third time this mistake has occurred and we are far from satisfied with the service you offer. Please ensure that this sort of problem does not arise again.
And finally, while writing the complaint remember that the person who you are writing to wants to correct the mistake and help you. He or she is not in business to irritate or confuse customers but to offer them a service.
Explaining the problem
If you think you know how the mistake was made, you may politely point it out. Sometimes when a mistake occurs several times, you may be able to work out why it is happening more quickly than the firm you are dealing with.
Suggestion a solution
If you think you know how the mistake can be corrected, let your correspondent know.
The best solution would be for me to return the wrong articles to you, postage and packing forward.
Rather than send a credit note, you could send six replacements which would probably be easier than adjusting our accounts.
