467. I am writing to you to complain about...
我寫這封信是為了投訴...

六級詞匯講解:
本句型是典型的投訴信件的開頭。complain about sth.是固定搭配，表示“抱怨某事物”，about不能替換為其他介詞。

句型拓展:
I am writing to express my dissatisfaction with your service.
我寫這封信是想表達我對于你們服務的不滿。
I beg to call your attention to the fact that your service is very dissatisfactory.
我想請你們注意，你們的服務非常令人不滿。
1 wish to refer you to an incident which occurred last Friday, calling for some remedial action.
我想告訴你，上周五發生的事急需采取補救措施。
I very much regret to have to inform you your service is very dissatisfactory.
很抱歉地告訴你，你們的服務非常令人不滿。
I am totally disappointed to find that your service is very dissatisfactory.
你們的服務非常令人不滿，對此我很失望。