Cancelled Account still being charged for.

On 31 May I made the effort of going into a Telkom store to give 30 day notice to close an account. I still paid my R999 that month even though I didn't use the 100Gig Data. We upgraded to an uncapped service provider because Telkom refused to hear our request to please give us uncapped wifi and stop raping us with their out-of-bundle data charges. The following month Telkom once again took the R999 off my account. I called their call centre, case number ********** 8, once again and cancelled AGAIN. Today I get a bill for R3287.40 from Telkom. They are still charging me, and this is also negatively affecting my credit score. How do I get to speak to somebody that actually knows what they are doing at Telkom? I go to all the trouble to do things right, yet they still do not do what they should do.