WASP charges still continues after cancelling

This will be the 3rd month where Telkom keeps R69 extra on my data contract for "Account subscriptions & once-off charges". I previously called them to say I never agreed to it, I was told to cancel it using the USSD prompts. I removed the sim from the modem inserted in a phone and did accordingly. I also cancelled with them telephonically and each time I call they tell me it will be removed from the next bill. They can access my history and listen to the calls where they keep making unkept promises. My confidence in them is at an all time Low!