We apologize for the delay and reassure you that we are doing everything possible to complete your order as soon as we can. We'll be in touch with an updated delivery timeline. I appreciate your patience; we'd like to offer you 10% off your next order.
Start with a clear, direct apology. Begin the letter by stating ``I am writing to apologize for the late delivery of your order.'' Take responsibility for the delay. Explain the reason for the late delivery, but avoid excuses. Express empathy for the inconvenience caused. Offer a remed