You installed their software when they told you that you needed it to connect to their network, right? Go into your Control Panel > Programs and Features and remove the Charter software.
The browser hijacks are installed as part of a media/advertising package. As an IT engineer of 20 years, I can tell you without a doubt that you do not need any software to use their network.
That’s not it. It seems to be delivered from the router, or perhaps beyond. I have no charter software on my computer.