You can create you own pre-set message for WhatsApp. This message will in the WhatsApp message box for visitors that click on the WhatsApp icon on your website. This is how you do it:
Click on the WhatsApp channel and enter your phone number
Click on the gear button and enter the message that you want to be pre-set for your visitors
Click on the Save button
When your visitors click on the WhatsApp icon on your site, you pre-set message will appear in the message box for them
This feature is available in the Pro version of Chaty