Dear Mr./Mrs. XYZ….
humble submission to state that, we now have received your letter acknowledging receipt in the items we mailed for your requirements and noticing us to cancel shipment of your order for those items which are back ordered.
We are issuing you a refund after we have completed the mandatory paperwork and other document for your account.
We wish to take this possibility to thank you for buying through (name) Our fresh (specify product or …..) catalog should be arriving at your house/office shortly, and I believe you will be pleased by some from the beautiful choices our buyers have made there is much surprise.
Thanks a lot for your patience along with understanding and for providing us while using the opportunity to be of service to you.