Hi Peter,
Thank you so much for your reply, and for pointing me to the file I need. I had also assumed this would be either a canned response, or at the very least, a localization string that I could modify.
I am frustrated that something like this is buried in the 'back-end' and not available in the Kentico "Chat" node. I don't have access to any files outside of the CMS, so I am going to have to call in a favor with someone else in order to change it!
Thanks again,
Deb