Support Hours built-in in WHMCS
Being WHMCS a support tool with built-in ticketing functionality, it should have "support hours" built-in.
That is, allow us to define "support hours" or timetables. For example, my working hours are from 8am to 14pm and 16pm to 18pm.
I'd like that when a customer sends a ticket (or an email processed by email import feature) when the business is closed, that he receives a ticket response where I can say something like "We're opened from 8-14h and 16-18h". But when the customer opens a ticket in opening times, I don't want that message to be seen/received.
I've seen your doc with instructions to achieve something similar (https://docs.whmcs.com/Editing_Client_Area_Menus#Add_support_hours_and_a_custom_message_to_the_sidebar_on_the_submit_ticket_page) but it's not easy and it should be built-in.