Dear :

Please accept our apologies for sending you merchandise that you have not ordered. You are certainly justified in being angry about our blunder.

Would you please return the wrongly delivered merchandise and enclose a note to our office stating why it is being returned. You will receive immediate credit for the returned merchandise and all shipping charges.

Again, I am sorry for the inconvenience to you. We do value your business and your friendship.

Sincerely yours,

[name]

[title]