Complain

I am writing to express my dissatisfaction with\at…

我写这封信是想告诉你们我对________不是很满意。

I very much regret to have to inform you that…

很遗憾地通知你，__________。

I would like to draw the attention of the authorities concerned to the …

我想就_____________问题引起有关部门的重视。

I feel something ought to be done about…

我觉得________方面还可以作一些努力（需要改进）。

I hope that the above situation will be improved as soon as possible.

我希望以上问题（情况）能尽快解决（改进）。

Your effort to provide good services will be highly appreciated by all.

我们会很感激您作出的一切努力。

We will appreciate your willingness to make up for the loss.

我们真的希望你们能对损失作出补偿。

Inquiry

I would like to request some information about…

我想对_______问题向您咨询。

My first question is… 我的问题就是__________。

I am greatly concerned about… 我对_________较为关注。

Should I need to send further materials, please let me know.

我是否需要再寄其他资料给你，请及时告知。

Could you be so kind as to send me some relevant booklets on the above-mentioned aspects.

能否针对上述的问题寄些相关的小册子给我。

结尾部分：

Again, I would like to express our warm thanks to you.

我想再次对你表示感谢。

I am looking forward to a favorable reply at your earliest convenience.

我希望待尽快给我回复。

Thank you for your consideration and I will be looking forward to your reply.

谢谢你关心（关注），我期待你的回复。