Can't cancel my fixed line

<p>I've been trying to cancel my fixed ADSL landline for the last 4 months. To date it's still not done after numerous emails and phone calls.</p> <p>Their billing system seems to be working though as I’m getting hundreds of phone calls and messages informing me of my outstanding balance and that I need to pay it to avoid legal action.</p> <p>I’ve gone into a branch to get my new LTE router and I couldn’t cancel it there. I’ve phone to cancel it then they told me to email them which I’ve also done. So what should one do more than that to cancel a service?</p>