Quote Originally Posted by LAGO View Post
What you just described is false advertising. Definition by lawyers.com: the crime or tort of publishing, broadcasting, or otherwise publicly distributing an advertisement that contains an untrue, misleading, or deceptive representation or statement which was made knowingly or recklessly and with the intent to promote the sale of property, goods, or services to the public.

It is illegal.
The key is "knowingly." Honest mistakes are not covered by this. Now, if they refused to return the person's money after correcting the mistake, that would be illegal.