telkom service stinks and staff is waste of time

i have been trying to cancel a land line with telkom for the past two months every time they say they will do it and sweet nothing gets done now i will not pay the account as they will be forced to cancel the account and every time i must send same docs to cancel when they do not do there job i need a answer telkom staff in the call center are useless and at the branch you only get can not do it who do i need to speak to cancelling land line