Peacock Premium Plus ad free

So, I just learned that Xfinity will not let you pay for the upgrade from their free Peacock Premium to Premium Plus ad free as of March 2026.  I was told by customer support that I had to go to the Peacock site and pay for the upgrade there.  When I go to the Peacock site, it will not let me upgrade my account because it says that my account is managed by Xfinity.  So how do I upgrade it?  I am just a wifi customer and I do not have Xfinity TV service.