投诉信开头常用句式和套话
I am writing to complain about/that...I am writing to make a complaint about...I am writing to express my concern/ dissatisfaction/disappointment about...I am writhing to advise you that I find... unsatisfactory.
投诉信开头常用句式和套话
I feel bad/sorry to trouble you but I am afraid I have to make a complaint about...I wish to draw your attention to the problem  /fault...that I bought...I am most reluctant to complain, but...It is with great reluctance that I must inform  you that...
投诉信结尾常 ...