Apology Letter For Overcharging

Dear {Recipient},

It has come to my attention that your credit card was overcharged for order number {number}, placed on {date}. It seems that the mistake was caused by {reason}. Our team is already fixing the situation, and you can expect the excess amount to be returned to your account in {number of} working days.

I apologize for any inconvenience caused. If you have any further concerns regarding your account or order, please don't hesitate to reply to this message.

Thank you for your understanding!

{Your Name}, {Your Position}