当买方是错误发生的责任方时，一封措辞恰当的回复就更有必要。通常卖方也会满足买方提出的要求，毕竟客户是他们生意的根本。因此卖方必须尽快礼貌地回复、并说明他们不是问题的责任方。

在回复的时候，如果确定要同意对方的要求，就应该先表示对要求的同意，然后说明责任是在买方。最后还是要表示继续贸易往来的愿望。切记不可以这样说：We are granting your request but we want you to know we don't have to. 这比拒绝要求更糟糕。

下面是答复这类索赔和投诉信应遵循的原则：

1. A statement granting the claim graciously.
2. A statement referring to the specific transaction.
3. A statement explaining tactfully and discreetly how the buyer is at fault. Take care to avoid causing him or her "losing face".
4. A sales appeal, if appropriate.
5. A friendly close.

下面是一封对此类索赔和投诉信的回复：

Dear Mr. Cooper

You will be enjoying new engines which we delivered to you yesterday. They will reach you no later than August 10.

We received your letter of July 30 in which you requested that we replace two MG - 02A diesel engines with two MG - 02B units. We are sorry to learn that the MG - 02A engines which we shipped to you on June 6 did not prove satisfactory.

Our representative looked into the matter immediately with our chief engineer in your city because we are always desirous of furnishing our customers with the best and most efficient machines. They found that a MG - 02B engine is recommended to be used for your particular diesel generating set. Apparently this must have been overlooked by some people in your firm when MG - 02A units were ordered.

Of course, we realize that sometimes an incident such as this occurs and we are sending the engines you requested. We are sure that the newly delivered models will meet your satisfaction and offer you the most efficient performance of your diesel generating sets.

Please send back the original units by the first available vessel. If we can assist you in any way in future, please let us know.

Sincerely yours

（例文来源：《国际商务写作教程》，对外经济贸易大学出版社 英语点津 Annabel 编辑）