We've got you covered with 25 customer apology letter templates so you can swiftly say "I'm sorry" and start delivering a solution. Find out what goes into writing effective, heartfelt customer apology emails with these best practices and free templates.Don't know how to write an apology letter to customer? Letter of Request addressed to the Director of Immigration. Copy of the Refusal Letter. 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. Find Apology Letter Format with Sample Template for Example. 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.