You may want to experiment with adding an "Emotional State" option to your support form following the Wufoo approach. They say that a large number of people fill it out and the byproduct is that people use calmer language because they are conveying how they feel through the dropdown instead of having to do it in the text.

edit: Here's the link to their blog post: http://particletree.com/features/on-asking-users-for-their-f...