Terrible service delivery experience with Telkom

My parents moved into a retirement village and we had to cancel their Telkom line. On cancellation Telkom informed us that they could not proceed with the cancellation as the service number has a DSL with another ISP and that we must first cancel with the ISP. My parents stayed in that house for 20 years and never signed or request a DSL line, until today they still do not have internet. I have been on the line with various Telkom employees now, the issue was escalated to several higher levels, the same message comes back every time. I CANNOT cancel an agreement that I do not have. You do not get past call centre staff and you cannot get hold of any manager to assist you. Although a number of the call centre staff treated me very kindly, the Telkom bureaucracy and operating system obstruct real issues of their residential clients to be resolved. A terrible experience that I have with Telkom, and an issue that I do not how I am going to resolve it. The line is obviously still not cancelled, and I get zero feedback from the helpdesk.