6mbps Speeds. 20mbps Billing.

I have been paying for a 20mb line from Telkom for the last 6 weeks or so - and still paying for that 20mb line. However I have barely been getting 6mbps. After several faults being logged, I got a call from OpenServe who confirmed the problem has been sorted out, only it wasn't and the lady on the other end noticed my line was synced to 5mbps. This has always been 20mbps for the last two years and every time a technician gets sent out to 'fix'the problem, but I am STILL getting 6mbps. VOX, my ISP, has done checks on their side and they can confirm that it's just on Telkom's side. Why am I paying the full amount for a service that's running at 30% of the capacity? That's not fair, considering for the last 6 weeks I have been getting a subpar service.

Refs: 111CWZ140618 and 157CWZ300718