Being billed for a service which wasn't asked for and isn't being used

It has now been 4 months (if not more) since Vodacom has been billing me for 'Interim LTE' usage, while waiting for Fibre to be live, even though I've stated that I don't want this, nor do I need this, as I have an existing ADSL Service through Vox, which serves my purpose. I've contacted Vodacom NUMEROUS times and every time I am told that the Interim LTE order will be cancelled and that I will be refunded. This hasn't happened to date. I'm tired of speaking to your call centre staff who follow a generic script when dealing with customers, but who also can't solve issues which Vodacom has created, but which I'm paying for.