A complaint letter informs its reader that you are not satisfied with a product or service. You may receive defected products, poor service or wrong merchandise. Writing a complaint letter is a way to show your dissatisfaction. More importantly, you would request replacement of or compensation for defected products or service. Before writing the letter, you could make a list of your complaints. A clear list is helpful when you write the letter. It also helps you calm down and prevent from expressing your feelings with angry words.

In the opening paragraph, you explain the reason why you are writing. The body of the letter provides all the necessary details and gives a complete explanation. Based on the details of your experience, you could politely tell your reader what action he (she) is expected to take. In the closing paragraph, you express confidence that the issue will be handled satisfactorily.

When receiving a complaint, you need to confirm the facts of the situation and answer the letter promptly. If the complaint is justified, you need to apologize for the error or fault, give a brief explanation and offer specific solutions. If the complaint is unjustified, you should give a convincing explanation why you are not at faults. Then you decline your reader’s requests. You may provide constructive suggestions to show that you really want to help.

日常商务活动或办公环境中，常会因为一些问题向卖方或相关部门投诉。如买方发现购买的产品或服务没有达到预期的要求和事先的约定，就可以通过写投诉信的方式表达不满并寻求解决方案。投诉信通常包含：解释遇到的问题、导致的结果、提出或期待解决方案。当收到投诉信时，首先应调查情况是否属实，然后根据实际情况作出及时、迅速、合理的答复。如投诉属实，确实存在失误，应承认错误，诚恳致歉；如投诉不属实或并没有任何过失，也应该礼貌答复，并加以澄清。