Dear [Customer's Name], We would like to extend our sincerest apologies for the accounting error in your recent invoice. Mistakes happen, but we understand the inconvenience this may have caused you and for that, we are truly sorry. At [Company Name], we prioritize accuracy and professionalism in our work, and we deeply regret any confusion or frustration this error may have caused you. Please rest assured that immediate measures have been taken to rectify the mistake and prevent its recurrence. Upon careful review, we discovered that the error occurred due to a technical glitch in our accounting software, which resulted in incorrect calculations on your invoice. We deeply apologize for any inconvenience or concern this may have caused you. Our team of experts has already addressed the issue and implemented additional quality control measures to mitigate any future accounting errors. We recognize the importance of maintaining trust and transparency with our valued customers like you. Therefore, we have taken the necessary steps to ensure that your corrected invoice is accurate and reflects the precise amount owed. You will find the updated information attached to this letter. In recognition of the inconvenience caused, we will be applying a 10% discount on your next invoice as a gesture of goodwill. We genuinely value your business and want to reaffirm our commitment to providing you with impeccable service and accurate accounting. Our dedicated customer service team is available to answer any questions or concerns you may have regarding the corrected invoice. Please do not hesitate to reach out via phone at [Customer Service Contact Number] or email at [Customer Service Email Address]. Once again, we sincerely apologize for any inconvenience this accounting error may have caused. We are deeply committed to improving our processes and ensuring such errors do not happen in the future. We truly appreciate your understanding and continued support. Thank you for your patience and cooperation. Sincerely, [Your Name] [Title/Position] [Company Name]