Take a proactive step and apologize to your customer. You can do this when you’ve advance information about the error. When you or your staff spots the bungle, go into the damage control mode sooner. Such measures convey the message that your company strives for world class customer service where the customer comes first. Further, your remedial steps help douse a spark, which otherwise would transform into a fire. What if the client raises the red flag before you find out the mistake? Again, in almost all cases don’t wait to apologize and fix the problem and prevent your company's reputation from taking a dive.