Voicemail Notifications

Voicemail Notification is not working on two new S20 Ultras. VM app gives message: Please contact Xfinity Mobile at (888)936-4968 to enable Visual Voicemail for your phone. I did this and the rep had me reset network settings, power off, switch to WIFI and more...nothing worked. He stated that Visual VM was set up and there was nothing else he could do. I reset to factory settings and we still do not get VM notifications. Notifications are set to allow on VM app and we are using the VM app that came with the phone since the Xfinity Visual VM app states it is not compatible with the device. Was missing too many messages, now having to go into VM daily to see if there are any messages...not the way I want a phone that I paid over $1000.00 to perform. This needs to be fixed. If someone knows how to fix this please advise. Thank you