Apple Watch cellular issues

I just received a Apple Watch. I purchased it directly from xfinity. It will not connect to cellular, Apple can’t help me, and no one at xfinity can help me! I have spent 10 hours on the phone today. Tier 1, tier 2, and a supervisor. Apparently they say tier 3 can not speak on the phone and can only email other xfinity employees. No one can help! Can anyone here point me in the right direction?