Peacock Premium as a Diamond Reward

I joined Xfinity Rewards and saw my tier is Diamond.  I tried to claim free Peacock Premium as a reward but can't activate it.  I did get the email with the link but when I click to the link I get a page that says my Xfinity plan does not include Peacock.  When I access the Peacock app on my TV box it uses my old Peacock account (when it was free) and requires me to subscribe for any of the Peacock offerings.  I tried to cancel my old Peacock account but that option was not available on the Peacock site.  Can you please help?