Compliants of over billing since January and nothing is being done about it

My mum is on the smartvoice 100 plan since September 2019, however since January 2020 she has been excessively charged for calls that she should not be charged for. She is entitled to 3000 minutes of Telkom to Telkom (both fixed and mobile) calls per month, but she is being charged for Telkom to Telkom calls, both fixed and mobile, even though she has not even used half of the 3000 minutes available in a month. She is entitled to 100 minutes to other networks and again she is being charged for calls to other networks, even before the 100 minutes is used in the month. Numbers that appear under "other operator", also appear under "calls to SA networks", Calls, that are under "mobile" and also included under "calls to SA networks" and numbers that are under "national Calls" are also included under "Calls to SA networks", all of this is on the same bill, this clearly shows that you inconsistently classify calls.

She has called the Telkom call centre on numerous occasions since January 2020, with the actual dates of her calls being, 20 Jan 2020, 28 Jan 2020, 24 Feb 2020 and 28 Feb 2020, during these calls she received the following reference numbers: *** and ***. She has been repeated told that "it will be sorted out this month" from her first call in January and now we are in May 2020 and this has not been rectified and since January to date she is still being excessively charged. This is causing financial constraints due to your staffs and entities incompetence, even though it has been brought to your attention numerous times, nothing is being done about it, as every month she is being charged approximately 50% more than she should be charged. She need to be refunded or credited immediately for all of the excessive billing as she has still being paying the amount per the statement every month to ensure that that she does have telephone services.