“Dear [Customer], I'm sorry to say that the product you received is of poor quality. We strive to provide the best possible products and services, and I apologize for any inconvenience this may have caused. We would be happy to replace it with a new one.
How do you write a negative letter to a customer?
Segue Into the Bad News Message
You don't want to sugarcoat the bad news, use euphemisms that make it difficult to understand what happened or explain more than is necessary. Also, do not apologize excessively. Instead, succinctly explain what happened, how it affected the client and apologize.