Dear [Customer's Name], We hope this letter finds you well. We are writing to apologize for the accounting error that occurred with your recent transaction with our company. We take full responsibility for this mistake and want to assure you that we are committed to resolving the issue promptly and ensuring such errors do not recur in the future. At [Company Name], we understand the importance of accurate accounting and the impact it can have on our valued customers like you. We deeply regret any inconvenience or confusion this error may have caused. Rest assured, we have already begun investigating the matter to identify the root cause and take corrective actions. The error occurred due to a clerical oversight while processing your invoice. We inadvertently recorded the wrong amount for the goods/services you purchased from us. Our accounting team has thoroughly reviewed the situation and rectified the error. We have immediately updated our records, ensuring that the correct amount is now reflected for your transaction. To further compensate for any inconvenience caused, we would like to offer you a [percentage]% discount on your next purchase with us. We truly value your business and want to express our gratitude for your continued trust and support. You will receive a unique coupon code through email within the next 48 hours, which can be used during checkout on our website or presented to our staff at our physical store. We want to assure you that we have implemented additional internal controls and reinforced our training procedures to avoid similar errors in the future. Our accounting team will undergo refresher training to enhance their attention to detail, ensuring accurate records and seamless financial transactions moving forward. Once again, we sincerely apologize for any inconvenience caused by this accounting error. We greatly appreciate your understanding and patience. If you have any questions or concerns, please do not hesitate to contact our customer service department at [phone number] or [email address]. Our dedicated team will be more than happy to assist you. Thank you for your continued support as our valued customer. We look forward to serving you with utmost professionalism and accuracy in all future transactions. Warm regards, [Your Name] [Position] [Company Name]