[Your Name] [Your Address] [City, State, ZIP] [Email Address] [Phone Number] [Date] [Customer's Name] [Customer's Address] [City, State, ZIP] Dear [Customer's Name], Subject: Apology for Accounting Error and Ensuring Accurate Billing I hope this letter finds you in good health and high spirits. I am writing to sincerely apologize for the recent accounting error that occurred in our billing system at [Company Name]. We deeply regret any inconvenience or confusion this may have caused you. At [Company Name], we strive to provide impeccable service and to maintain transparent and error-free financial transactions. Unfortunately, due to an unforeseen technical glitch, your recent invoice [invoice number] inaccurately reflected the charges for [product/service]. We take full responsibility for this mistake and have immediately rectified the error in our accounting system. The correct invoice [new invoice number] has been generated and is enclosed with this letter. You will find that the new invoice accurately reflects the charges for the [product/service]. Moreover, to assure you that such errors will not occur in the future, we have conducted a thorough review of our accounting processes and implemented additional checks and balances to prevent recurrence. Our team has retrained on the importance of accurate invoicing to avoid any similar mishaps, in appreciation of the impact this may have on our valued customers like you. Once again, we sincerely apologize for any inconvenience this might have caused you and assure you that we will make every effort to ensure such errors are avoided in the future. We truly value your continued patronage and the trust you have bestowed upon us. It is our commitment to provide you with exceptional service and flawless financial transactions. If you have any questions or concerns regarding the new invoice or this accounting error, please do not hesitate to contact our customer support team at [customer support number] or by email at [customer support email]. We are available to address any queries you may have promptly. Thank you for your understanding, patience, and continued support. We genuinely appreciate your business and the opportunity to serve you. We will do everything within our power to regain your trust and confidence in our services. Yours sincerely, [Your Name] [Your Title/Position] [Company Name]