投诉信的英文：
letter of complaint

参考例句：

He stormed into the office, flourishing a letter of complaint.
他挥舞着一封投诉信冲进了办公室。

He rushed into the office, flourishing a letter of complaint.
他急冲冲地闯进办公室，手里挥动着一封投诉信。

letter是什么意思：
n. 字母；信；字面意义；证书，许可证；文学
v. 用字母标明，写字母于；写印刷体字母；赢得校名缩写字母标志

in letter and in spirit
在字面意义和精神实质上|无论形式和实际

The letter was a forgery.
这封信是伪造的。

Post the letter through the slit in the letter box.
把这封信从信箱的投信口投进去。

Imprint a postmark on a letter =imprint a letter with a postmark
盖邮戳于信上

The letter is directed to him.
这封信是写给他的。

complaint是什么意思：
n. 抱怨；抗议；控告

Viewers jammed the switchboard with complaints.
打电话投诉的观众是总机应接不暇。

I recounted Egyptian complaints.
我重述了一下埃及方面的不满意见。

He was irritated by their perpetual complaints.
他们不断发牢骚把他惹火了。

Students made a rash of complaints.
学生们发出一片抱怨声。

To relay any customer complaints to supervis.
处理并向主管汇报客人的投诉。