A Letter of Complaint投诉信是当人们对某机构的工作人员或其服务不满时，向有关机构的主管或监督人员所做出的书面表述。其内容往往包括对被投诉事件的回忆，投诉人的心里伤害、经济损失，以及投诉人对被投诉方提出的合理补偿要求等。
1. I am writing to inform you that I wish to move into a new room next term. I would prefer a single room， as I find the present sharing arrangement inconvenient.
2. I am regretted to inform you that the heating system in the house stopped working a few days ago.
3. I request you to arrange to replace this Walkman with another one， which must be in perfect working order. Failing that， you must have a full refund.
4. It is hard for me to understand…
5. I am afraid that I have a complaint to make.
6. I hate to bring this up， but…
7. I am not at all satisfied with…
8. I want to complain in the strongest term about…
9. I am really annoyed about it.
10. I am regretted to say that sth. was incorrect.
1. I feel terribly sorry to hear what you said.
2. sth. must be done about it.
3. I will immediately attend to it so that I can give you a satisfactory response.
4. Please forgive what we did to you and accept our sincere apology.
5. There are three ways we can handle this situation.
6. We do wish you could be satisfied with what we have compensate for the trouble we made.
7. We have communicated with the concerned person， confirmed what you had complained， and punished him.
8. We will have him apologize to you on the day you appoint.
9. We do value your business and friendship.
10. We would have refund and hope that you could accept our sincere apology for the mess we made.