billing

I cancelled an account and started a new one at a different address.  I continued to be billed at the old address.  I have had 4 coinverstions with agents to work this out and got a written notice that I was owed $660.23 but now have had service cut off because i woe money.  Each agent "corrects things" but then my service goes out againd for owing money,  it is very hard to talk to an agent.