Helpppppppppppppppppp

Ever since the March 2016 so called UPDATE I cant sign in using iPhone 6+!!!!!!
Never ever ever had a problem. Ive restarted. Ive reinstalled. Always the same result at sign in.... Error 500. How can I go back to the previous update which had ZERO Problems!!!!!!!!
I want my home TV back on my iPhone!

CatheeG about Xfinity Stream