We have been bombarded with letters of complaint.

我们接二连三收到了大批的投诉信件。

《牛津词典》

Letters of complaint continue to pour in.

投诉信纷至沓来。

《牛津词典》

Letters of complaint poured in.

抱怨的信件源源而来。

youdao

But similarly named correspondents have been composing slightly humorous letters of complaint since the mid-19th Century.

BBC: Disgust: How did the word change so completely?

The three appeal judges were informed that letters of complaint are also to be sent to the Public Prosecution Service and the Law Society, amid concerns that covert surveillance may have been used against either the witness, his solicitor, or both.

BBC: Constable Stephen Carroll

Since then it has attracted more than 90 letters of support but 63 of complaint, including objections from the parish council.

BBC: Hall plan using money left to village attracts complaints