Impossible to cancel

I have been trying to reach a real person since I returned my untouched modem to the xfinity store because i never had a coaxial port or hook up internet. I have NEVER Used it and i am still getting emails for a bill. When I try to call to cancel I cannot reach a single real person, and when they call for the bill and try and transfer me the call gets dropped. This is the worst customer service experience I’ve had in my life with a company.