Bad Attitude of my customer

I had a bad experienced to a bad customer today. While I am busy updating my blogs there's two customer suddenly want to log-out and pay their time. I ask them what is the problem because I felt that there's something wrong. The guy said that “ your computer is can't works properly, we want to copy and paste our files but its not work”. I suddenly go out and ask them what their files so that I can assist them and to know what is the problem why our software can't accept their files. They both sit back and surf again but before that they said that they set their time in one hour . I assist them and I the only one who copy and paste their files after finished copying their files there's nothing problem happen. I told to the guy that do not copy all word with the picture because there's a possibility that the files will be a error. After that I leave them and he continue of what I teach him. After that it takes a time I remember that they set their time only one hour but before I set it again I asked them if they continue or not ? badly he shouting me and said “ I told you that you set one hour” I really shocked. It's really bad I don't expect that it will be happen.