Your best chance is to chat with the support team.
Go to the Help secrtion in the web site or in the app and start a chat via the chat bubble at the bottom right in the page
You can try this also:
Hello Nickita_Aurore, Thank you for opening this thread. Please note that for the installation you don’t need to be in person at home. Any 18+ person can be there to welcome our technician. In case no one can, you can rechedule the appointment from your account by going at: My plans → Manage my plan → Installations. In this menu you can see the time slot of your appointment and you have the option to reschedule for another day (You will see a calendar live updated with free slots, same visibility as we have over the the appointments of our technicians. Don’t be afraid to verify, your current date won’t be lost if you won’t finish the process by selecting a new date.) If you have other questions you can contact us anytime in private from this link: https://fizz.ca/en/support I wish you a great day, -Georgian