Say that you are sorry and regret that you could not deliver the order on time,and tell them why it was not delivered on time. We've got you covered with 25 customer apology letter templates so you can swiftly say "I'm sorry" and start delivering a solution.In this article, we'll cover everything you need to know about writing apology letters and provide 5 templates you can use to get started today. Don't know how to write an apology letter to customer? Below are 4 example apology letters you can use and make sure to give them a way to contact you in case they have further questions. Making a Sorry for Out of Stock Item Letter online is simple. Just answer a few questions, and Rocket Lawyer will build your document for you. Find out what goes into writing effective, heartfelt customer apology emails with these best practices and free templates. The letter apologizes for inappropriate behavior on a certain day. It acknowledges the behavior was disrespectful and disrupted others.