Need to talk to a supervisor

I returned the TV box as instructed when I cancelled my Internet and Cable (Not mobile).  The store agent gave me a final bill amount.   I chatted with an online agent for over 20 minutes on what the charge was for.  They couldn't tell me however, gave me the same final bill amount as the store agent.  I thyen talked to an agent on the phone (Akshat) for an hour who saw the same final bill number but couldn't tell what the charge was for.   When I asked to speak to his supervisor, he told me that not only was I not allow to talk to them, he wouldn't even give me their name.  Is this really how you run your company.  I has in the Services Industry for 40 years.  Xfinity has to do better.