1表达歉意：There's no excuse for … I forgot to ….
I am indeed very sorry for …, but believe I had no intention to…
Here is my deepest apology for ...
Please forgive me for …
2解释苦衷：The fact is that I had …/ Unfortunately I …/ I had a small accident …/ I have some urgent business to deal with My behavior yesterday was inexcusable, and I must tell you how …
3请求原谅提出补救方法：I want you to know how badly feel about… and to assure you that it will not happen again.
I realize that particular… is irreplaceable, but I hope you will use the enclosed check to purchase a similar one.
I hope this situation can be mended to everyone's satisfaction.
I can only hope you will forgive … on my part.
You have received a complaint letter from your customer for the mix-up of order #: 26429782. Write a letter to him to 1) express your apology 2) explain the reason 3) provide the solution and offer the compensation.
Dear Mr. Bicman:
I apologize for the mix-up of order #: 26429782. We have just implemented a new packaging system that still has a few bugs to be worked out, but we did fix your order and sent it out this morning. For your trouble, we have enclosed a $25 gift certificate which can be used at any of our stores. Once again I would like to apologize for the mix-up in your order and any inconveniences this may have caused you.