What can you do when someone just doesn't get it?

Walk away.

W/out knowing more details…..based on what you have said….it sounds like they are hearing you….just that they don’t like what they are hearing.

Talk to the person in front of another, who can help moderate the discussion.

Throw things at them.

Really, though… Are you sure you want to be communicating with this person? They sound very stubborn. Usually patience does the trick, but it seems that you’ve been working on this forever. Time to back away?

I like skfinkel’s idea, too.

How invested are you in the person seeing your perspective? Is there some action required of them, that requires them fully understanding you?

If it’s really important that you get your point across and you’re not doing so, skfinkel is right on. One of the only ways to see what your communication problems are is a moderated discussion.

Billboard?

Wait in backseat of their car till they leave work wearing a clown suit and a burlap sack with the eyes cut out, Put a large caliber pistol to the back of their head. Calmly yet forcefully explain your point of view through a voice disguising device. Then exit the car and play the wait and see game… Or do what skfinkel said that might work too. : )

Raise your voice and put an angry tone to deliver your message.
Start tackling what they are thinking and attack their points.
Normal people will be able rationalise what is correct and wrong. Slowly correct them if they are beginning to accept it.

Stand about two inches away from his face and scream as loud as you can your point of view. Just belt it out. Draw diagrams, create a Powerpoint. Bring along evidence that supports your stance and just let ‘er go. Don’t be complacent in your thinking or actions. Get him mad and let it crumble naturally. Don’t guard your feelings or actions, or those of others. It is what it is, everyone will get there and they should. Even kids.

Unless it is imperative for this person to get the point, I would drop it altogether. It is obvious the point you are trying to make is either beyond their comprehension or they choose not to hear you.

It is imperative that this person gets the point. The truth of the matter is that I am the only person who can get the point across.