Thanks for letting us know and I'm sorry for the delay.
When connected to the Nest app and Wi-Fi, the thermostat automatically sets the date and time based on your location. It will also automatically adjust for Daylight Saving Time based on your time zone.
If the time is incorrect, update the zip or postal code in the Nest app.
If the thermostat isn't connected to Wi-Fi, you will be able to set the date and time manually. Check this link for more details on Nest thermostat settings.
Keep us posted.
I am truly sorry for the trouble and frustration that you are having with the device. I understand that is not the most ideal situation, and I am more than happy to assist. Since you have exhausted all troubleshooting steps, I would like to escalate this to a higher team.
If you could please fill out this form, our Team would then be in contact with you for additional support. Please let me know if you have any questions from here as well.