Write a letter acknowledging the cancellation of backorder.

 Dear Sir,

This is to inform you that we have received your letter acknowledging the receipt of the items we mailed to you and asking us to cancelshipment of your order for those items which are back issue you a refund as soon as we have We would also like to take this opportunity to thank you for shopping through (name) Our new (specify) catalog should be arriving at your home shortly, and I believe you will be pleased by some of the beautiful choices our buyers have made this season.

We will highly appreciate your patience and understanding and for providing us with the opportunity to be of service to you.

Thanking you 

Yours truly,

Name