One of the most popular pizza franchises, Pizza Hut, will be open on Christmas. Pizza Hut has a contact page on there website, as well as a virtual ordering system. For urgent matters their phone number is 1-800-948-8488(U.S.) or 1-866-664-5696(Canada.)
Pizza Hut has their own Facebook®page and you can sign up to receive emails from them on their website. And if your trying to find a Pizza Hut location near you, you can use their store locator.