Verizon not letting me reschedule an "installation"?

 They told me they would come tomorrow but I bought my own modem for the 300MBts up & down Internet service (all I need): Verizon Fios Gateway AC1750 Wi-Fi (G1100) and I just realized today the company I bought from had never shipped it, so I had to by from some other one.

 When I try to reschedule online, all I see is a message saying: "We are looking up your account information and checking for available services. This will only take a moment",  and then I am redirected to the page I was.

 I called them and they told me they could not internally reschedule that technical visit themselves?!?

Re: Verizon not letting me reschedule an "installation"?

Hi jweinberg,

Your issue has been escalated to a Verizon agent. Please check your Private Message Inbox for a message from Verizon_Support. You can find your Inbox by clicking on your username at the top right corner of this page. Please direct all correspondence concerning your issue to the agents who will be assisting you privately.

RE: Verizon not letting me reschedule an "installation"?

When I go: my account > Verizon Messages > Email and Texts:
 I see the last message I have received:
Updates made to your Verizon account   10/17/2018  12:53 PM

 but when I click on that last message, all I see is what seems to be a javascript-based message with no contect:
 Updates made to your Verizon account  10/17/2018

 and if I try again all I see is some javascript based nonsense: 3 balls alternating colors

 I received that date an unrelated email message relating to my account set up which doesn't seem to appear on those messages.
 Anyway, I was able to speak to them on the phone and they rescheduled my appointment for October 29th. I hope there won't be any more problems.