Bad service / No service / *********** / Call drop

I cancelled/ suspended my Telkom line on 08/10/2015 and pay them everything due to them. They still needed to refund me my R700.00 joining fee. This month 06/12/2015 I received a bill stating that I'm due to pay them R102.30. On the 18/12/2015 @ around 17h35 I called in and got through to the billings department (10217), I spoke to Thembelani, after he confirmed my details he ask me what's the problem and I told him that my line is cancelled but Telkom are still billing me, why and what is it for