Apology for unavailable goods, temporally out of stock
[Date] [Name] [Address] Dear [Name] Thank you for your order [Number] dated [date]. Unfortunately at the moment we are out of stock of [Product]. This is because [Reasons]. Our materials department, have informed me that we expect to have [Product] in stock again by [Date]. We will dispatch them to you unless we hear from you to the contrary. We apologize for any inconvenience this will cause you. Yours Sincerely [Your Name] [Your Title]