Port Forwarding Issues

Is there a way to get actual assistance with customer service? I have been having issues with port forwarding not working and I'm just getting run around by the support team. They sent a tech out for free and offered a discount on my internet. But the issue is still happening, I have done everything from get a replacement modem from Xfinity to purchasing my own modem, which I needed to do anyways. But I'm still unable to get any type of quality assistance at this point.