We all know the saying "The customer is always right" It should be revised.........the customer is always right, unless they have no idea what they are talking about due to a lack of information, then the customer is simply wrong.........and supplied with the correct information so that in the future they can be right.......but until that happens.......consider them wrong.
If they argue the point that they are indeed right.....when clearly wrong.....consider them a hostile customer and more than that.....an uninformed asshole.......politely supply them with the correct information.......if they still argue the point...........feel free to start the next sentence with....."listen up"