Telkom Complaint

Good Day I have a problem of not being able to get my landline disconnected for I have been in contact with Telkom several times via emails and phone contact but no response. This is becoming a severe problem for the fact that I am being charged interest on a monthly amount and this is uncalled for because I no longer need or use the line and have not been from November 2017. I do wish that the problem could be sorted soonest for it would save myself and Telkom money and time....