From Services, you have the ability to control the type of message that gets sent at the time of booking for the client.
You can edit the category by going to Services -> Click the blue view button on the service to edit.
Under Category, you can type in a NEW category name. As you type, you will see the drop down menu display "ADD NEW" this means a NEW category is being created -> From here, you can navigate away by either clicking away or clicking the TAB key on your keyboard -> Enter in the rest of of your service details -> Click SAVE.
Once the service has been saved, you can edit the content of that new category by going to Business Setup -> Your Clinic -> Message Settings -> Select the message option to edit (Booking SMS, Booking Email etc) -> From the service category dropdown, you will be able to select the NEW category that was created -> Ensure to give the message a subject AND body if you are working with the email section -> Once changes have been made -> Click SAVE.
The easiest way to edit a new category of messages is to copy across one of your other SMS or emails that have been setup and paste into the new category, then edit as needed.