Worst Service I Have Ever Received

I cancelled my business line more than a month ago following the call center instructions of sending a email to [Email Removed] containing a copy of my ID and a cancellation letter on a company letterhead. Even sent it a couple of days later again, as I heard nothing back from them. I mailed them a couple of times, but they never responded to any email. My line is still active after more than a month. Called the call center and they keep saying I must mail the above mentioned email adress. I will not pay anymore bills I receive.