I had some work completed in my home by a licensed contractor from a local HVAC business. I needed some repairs completed on the radiant heated flooring in the master bedroom and bathroom. The cost for the repairs was significant. I saw a copy of the bill before some changes were made. The other bill came in the mail and I was very surprised by the amount. The total for the charges didn’t add up to the amount they still wanted me to pay. I contacted the HVAC service company and I was asked to call back the next day to speak with their business affairs department. That seemed reasonable, but I was upset that I didn’t have anyone to help me that day. I called back the next day and got a voicemail. I left a message and the person called me back an hour later. I explained the situation with the charges and the estimate. The woman in the accounting office asked me to hold on the line. She was gone for a long time, but she came back to the line with great news. She found the other invoice and apologized for changing the numbers. The bill was off, because she mixed up a 6 and a 9. The mistake was entirely due to the bookkeeper and not an issue with the HVAC service team at all. The bookkeeper fixed the billing error and apologized several times for making the mistake and causing the problem. I didn’t mind the error as long as they fixed it and credited my account.