Thank you for bringing the recent error on your account to our attention. We have corrected the error and apologize for this error. The day your payment was processed, our computer system was down. Unfortunately, this resulted in the mistake on your account.
We...
Dear (recipient's name),
Thank you for bringing the recent error on your account to our attention. We have corrected the error and apologize for this error. The day your payment was processed, our computer system was down. Unfortunately, this resulted in the mistake on your account.
We appreciate your patience and thank you for your business.
Sincerely,
(your name)