You seriously made an appointment with someone who called you?  Why would you ever do that?  Obviously these people are scammers, but it is always best to get referrals from friends, look up reputable companies online (read reviews), etc.when you need work done.  NEVER do business with someone who calls you.  They either do an awful job, or they make you pay money up front, and you never see them again, etc.  Be cautious!