1、投诉信的开头常用句式和套话

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

I understand you will give immediate attention to this matter.

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

询问信的开头常用句式和套话

I would be most grateful if you could send me information regarding/concerning …

I am writing to see if it is possible for you to provide me with information regarding