Problem getting lines Cancelled!!!

I have cancelled my business lines at the middle of January and we followed all procedures and even emailed the cancellation to the email provided on our letterhead which telkom has received. We are still being billed for the lines and i have called the call center 7 times regarding the cancellation and all they can say is the lines are showing as cancelled on there system and they will look into it and call me back. and i never receive any reply back. My cancellation was sent to Daleen Julianne Theron and i have spoken to her regarding the cancellation but i am not getting anywhere with this matter and my lines are not getting canceled. I am loosing any hope in Telkom.