Wrong billing and not correcting their mistake

This is my 4th attempt for assistance with my DSTV account/subscription and online profile with wrong balance details. After a previous email and two calls for a supervisor to call me back I have not received any reply. <br> I activated my DSTV online 12 July 2015, my balance was on R0.00. I was prompted to pay R512.60 on 12 July for the subscription for the remainder of July. This was paid from ABSA via EFT. On the 25 of July 21h41 I scheduled a disconnection online for 1 August to prevent any future charges. This was never activated from Multichoice and now you still show an outstanding amount. Your call centre agent acknowledged the error when I called 16 September and promised that my balance will be adjusted to zero again or that a supervisor will phone me. Nothing has happened. Please sort this out and clear my balance. Please also delete all my decoder details I am done with DSTV after this terrible service.