supersonic is a NIGHTMARE!

My worst mistake in life was signing up with supersonic. I eventually cancelled my account because the connection was very poor, I was paying monthly for a connection that did not even work and I finally cancelled because I had also had enough of the poor customer service. The agents are rude and can put you on hold for over an hour. I thought my nightmare of dealing with Supersonic was over well I thought wrong, even though my account is on 0, I am getting harrased by VVM supersonic debt collectors claiming I owe them money. i have sent several emails to supersonic to take my name of that list but I have not received any response instead I am getting harrased and they are messing up my credit score.