Dear :

I am returning for repair the [product] we purchased from you days ago (Invoice #). The product is covered under warranty # (copy enclosed).

After the [product] had been installed, we found that the did not work. Would you please inspect the device and repair it for us? If the [product] cannot be repaired, I hope you will send us a replacement and make sure that it works properly.

Hope to hear from you soon.

Sincerely yours,

[name]

[title]