billing error continues

Each time I have looked at my Xfinity billing detail during the last three months I'm charged for a subscription I didn't make: Fox Nation.  Through Live Chat, I get the subscription canceled, only to have it reappear as an upcoming charge the next time I look.  How does this happen?  I use purchase pin codes and have changed passwords.  No one else here but me.  If the problem continues, how to I contact a higher level of management?