I am writing to complain about/that…

I am writing to inform you that I am dissatisfied with you…

I think it’s high time you realize…

I am writing to make a complaint about…

I feel sorry to trouble you but I am afraid that I have to make a complaint about…

I am writing to express my disappointment/ dissatisfaction/ concern about…

I am most reluctant to complain, but…

I am writing to advise you that I find… inconvenient

I wish to draw your attention to the problem / fault… that I bought…

I venture to write for complaining about…

I feel sorry to trouble you but I am afraid I have to make a serious complaint.

It is with great reluctance that I must inform you that …

I regret to inform that …

Thank you for your … which arrived yesterday. Unfortunately, …　结尾常用句式

I would be grateful if you could…

I trust you will take my complaint seriously and…

I will appreciate it very much if you could…

I must have you fully understand that without a satisfying solution, I will reserve my right to take legal action.

Frankly speaking, I am not prepared to put up with the situation any more.

On the condition that this one proves to be unacceptable, I will receive a refund.

I would appreciate it if you could…

I understand you will give immediate attention to this matter.

I look forward to your dealing with these problems without delay.

I would like to have this matter settled by the end of…

I shall be obliged if you will look into …

I understand you will give immediate reply to this matter.

If I must be constantly annoyed in this matter, I shall have to …

其他常用句式

The reason for my dissatisfaction is…

Under these circumstances, I find it difficult to…

I can no longer tolerate / bear…

For one thing… For another…

I hope we can manage to sort his out amicably.

Therefore, I hope to change for another … or I declare a refund.

We know that you are not generally careless, but we would like your assurance that this will not happen again.

I recently ordered / purchased from you …

I must protest against …

I find it appalling and distressing that…

I received such poor service that I felt I should bring to your attention.

If I receive this type of treatment again, I will take my business elsewhere.