Telkom Incorrect Charges - Refund of nearly R1000 2 months overdue.

At the beginning of March 2018 I gave Telkom 1 month's notice to cancel my home telephone service. There was no contract for the line. On 17 April I received what was supposed to be the final account. To my surprise I was charged notification fees of almost R950. I queried it on that day and they acknowledged that it is a mistake and they will resolve it. At the end of April they deducted R800 off my account. I queried it again, only to be told the query is still open and someone will contact me in 2 days. Nobody contacted me. I phoned numerous times with the same issue, each time spending nearly an hour on the phone, only to get the same response after speaking to numerous persons per call. Again, nobody returned any of my calls. End of May there was another deduction for R23. Yet again I gave numerous calls to Telkom, spending an hour on the call, speaking to at least 4 to 5 people per telephone call (including a supervisor). Once again, same story. Query is still open, it will be escalated and someone will contact me in 2 days. This is unacceptable. With the credits that were due to me Telkom owes me nearly R1000. This is a lot of money and I need to get it back a.s.a.p. How much longer do I have to wait for such a simple and straight forward query to be resolved?