Dear Mr M,
We are writing to express our deep concern at the problem recently we’ve run into.
We have been dealing with you for the last five years without any problems and have always been happy with the quality of the products you sent us. However, in the last several months, we have received at least three wrong stocks:
-in April, we ordered 500 women’s middy blouses in gray, but we received blue ones.
-we then bought 200 silk shawls in June but ended up getting 200 silk scarves.
-a week ago, we found out that half of the women’s sweaters we ordered turned out to be for men.
This is indeed a serious problem, which has cost us at least 50,000 dollars. We have always believed in your service and the commodities you supplied. Therefore we hope that you will look into this problem as soon as possible, lest it would harm not only us, but also your company’s reputation and even our future cooperation. We would be grateful if you could fix it straightaway, and we would like to offer any help you may need. If you have any questions about the points I have raised, please do not hesitate to contact me.
I look forward to hearing from you.
解析：这一栗子模仿上文，将邮件分成了五个部分。一句话表明来意，第二段示好之后委婉提出问题，下面具体指出问题所在。最后一大段包括两个部分，表明wrong stock对己方造成的损失，同时表示这一问题如果持续出现将不仅有损自己，还会损害对方公司的名声甚至将来的合作。注意，题目中要求写出如果问题得不到解决，自己将采取的行动，这里还可以更明确的写出，比如：If this problem continues, we might have no choice but to seek other partners.