Impossible to cancel voice line

I've been trying to cancel my voice line for the last 3 months. I've sent the email twice with copies of my ID but both times after the stipulated 21 days I received no response. So I decided to go to the store and cancel it, once again they took the same form and copy of ID saying on Monday I would receive a response for the cancelation. On Monday I receive a call from the person I dealt with saying the line was cancelled. But once again it's clearly not cancelled as I'm still receiving the bill. I refuse to pay this account as it's impossible to cancel.