Upgraded Service - Can't view "new" channels?

We recently upgraded our service and received a self-install kit for a new modem and a new DVR X1 Box. 

Installing the modem and the internet service is fine. But, when I attempt to watch the "new" channels on my new Cable Box, they are unavailable. 

I've spoken to two Comcast customer agents. The first indicated that they would "reset" my cable box and the problem would resolve in 1-2 hours. Unfortunately, it did not. 

The second agent I spoke to did a system refresh of my cable box and said the channels just "take a really long time to load" so it could take as much as 24-48 hours to see my new channels. 

It's been more than 48 hours and still no change. 

Connections are checked. Everything looks good. Again, I can see all the channels from the previous "starter" package. 

Examples of channels I can not currently see are CNN, Disney, ESPN, and HGTV. 

Error code I continue to see is: XRE-03121 

Thanks for any help you can provide.