Status update, Dell-Cares was able to assist with the scheduling of the service. 
A tech called me yesterday to confirm his arrival for today. An hour or so later I found out the laptop he is to repair will not be on-site when he arrives. I spoke to two different chat reps on the website who could not help, and I tried calling Dell but was put on hold too long and it was end of day so I had to hang up. I decided to reply to the email and let them know that way. I just want to help prevent the guy from coming to our site which is in the middle of nowhere if he can't do anything. Is there a way to update the tech/what is the best way? Edit: Just found a 'Reschedule My Appointment' button in the 'Service Request Details' page but it's greyed out.
Rescheduling Service Call