What do I have to do to cancel my Telkom ADSL line?

I have been tryng to cancel an ADSL line hosted by Telkom. When I sent in the cancellation request, I received the automated response which confirms that Telkom received the cancellation application. After a months silence and the 21 days have expired, they admit that it is on the system, but it does not get disconnected. Phone calls to Telkom all end in "we will escalate the problem". What do I need to do to get it cancelled?