Apology for unavailable goods, similar product available
[Date] [Name] [Address] Dear [Name] Thank you for your order [Number] dated [date]. We regret we can no longer supply this product because [Reasons]. However, we can provide you with a similar product. Please find enclosed details of this [Product]. If it meets your requirements, let us know and we will ship it to you. We look forward to hearing from you. Yours Sincerely [Your Name] [Your Title] Enclosure