Poor Service From Telkom

Another poor service from Telkom. I subscribed for two data sim cards 8 months back. They delivered three. After delivery I delivery phoned them to that I received one extra. The call agent advises me not make use of the third one and that they will not bill me for it. Sadly, I am invoiced monthly for the third sim card. Now every time I called them, they are investigating. One of the call agents asked me to send details of the Sim card not in use via email, which I did but even today nobody from Telkom can assist with my case and yet they keep billing for the service I am not using.