Try rebooting

Back in February, another user complained: “A popup keeps telling me "first a quick piece of business thank you for subscribing to watch this title you must upgrade your account" with this phone number (800)675-1111. The number only leads to a Busy signal.” This is still happening, though rebooting the AppleTV seemed to help, at least for now.

Flash Sheridan about STARZ, v3.3.1