Xfinity WiFi new service

I signed up for service to start a week ago. I bought my own modem. I tried to connect it in the app and it keeps telling me I have to purchase Internet after I already have a bill and I’m already signed up for Internet for one gig I have been trying to talk to the bad I tried calling. I can’t get a hold of anybody. My service doesn’t work. The app is not letting me connect my modem to continues to prompt me to purchase Internet. I called originally to sign up for Internet. I need to make an appointment to have somebody come out to my house to fix this. How do I get a hold of somebody? I also want to dispute my bill because now I have a week that I’ve been paying for nothing.