Why can't I see upgrade offers?

No matter how I try, I cannot see any plans or any upgrade offers on the website. I am trying to upgrde my cable plan to include HD, but all of the (apparent) ways to do so redirect me to a page that says "Good news! Xfinity service is included at your address. We've partnered with your community to bring Xfinity service to (zip code)". But I know service is included at my address, because I am watching tv right now. On my tv, when I try to watch HD channels, a pop-up appears that says ""To watch this channel in HD,  you'll need to go to www,xfinity,com and select Shop/Upgrade to add HD to your package" EXCEPT!!! no such option exists! So what is the truth? What is the deal? I just want to watch football!