As bad as it gets.
XDP have had my "next day delivery" chair in their depot for 9 days now. Yesterday I received the 'morning of' text to say that my chair would be delivered between 11:04 and 13:04, which would be fine had the text not been sent at 14:01! I assumed that meant arrival today, but alas it was intended for yesterday. We were home yesterday and no attempt for delivery was made.
As mentioned by others you can't call them to discuss, neither can Wayfair! Customer service is essentially an email address that you won't receive a response from (emailed them a week ago).