Dear :

We regret that we sent you [model] instead of the [model] that you ordered. Please accept our apologies.

We will ship the correct items to you immediately at our expense. Please return the wrong items to us by [delivery service], and we will credit your account for all the shipping and handling charges.

Thank you for your understanding and cooperation. We look forward to further business with you.

Sincerely yours,

[name]

[title]