I can't use my internet

I signed up for 2gb internet, put my credit card in and everything. But when I log into my account online I can't manage my account. The page won't load. I've tried clearing cache, cookies, going incognito, using other browsers. I can't log into the app which is necessary to set up my modem/router. When I login, it says I successfully logged in but im not authorized because im not an xfinity user... which I am... that's why my credit card is being charged.