Cancelling an Xfinity in-home appointment.

I have an appointment for Monday, Nov. 23 at 3:00 - 5:00 for a Comcast tech to come hook up services at my new home.  (order # 1001121383062040).  I was able to do all the connections myself and tried to cancel the appointment.  Calling put me on "HOLD" for too long.  I tried "CHATS" and after a number of transfers and an hour of frustrating chatting I was sent a confirmation text to my phone.  When I clicked on the link sent me I got the message "SOMETHING WENT WRONG.  TRY AGAIN"  There was no way to go back and try again without starting all over.  I still don't know if the appointment was cancelled.