Been trying to cancel my landline for months without success

I tried to cancel my landline since July 2017. Got a response that it can't be done because adsl was still active, okay fine. Tried again in August after adsl was successfully cancelled. No response. No response when I tried again September or October. When I tried again in November, I get told same excuse of adsl still active. Please just cancel my fricken landline. I have contacted my previous isp and they have confirmed everything is cancelled on their side. Telkom, why you always gotta be so useless?