Dear Mr. Lee,

Thank you for your e-mail concerning the two photocopiers you bought from us last month.

Our service manager, James Peterson, has examined the two machines and is unable to find any faults. Therefore, we are not able to provide you with replacement.

However, we will be happy to arrange for our sales consultant, Ben Sun, to call on you at your convenience to go through the main functions with you so that you are fully aware of its capabilities.

Please call me on 075-3287932, I will make an appointment with you.

Sincerely yours

Todd Gray

Analysis

Sample 4 是对 Sample 1 的回复。首先，确认收到对方的投诉信。己方如果有过错（Sample 4）需要向对方致歉并给出解决办法。如果己方无责（Sample 5），则需要把事情解释清楚，并拒绝对方的要求。往往我们可以给出一些建设性的建议，以帮助对方解决问题。