Disappearing data and airtime

Once again my airtime and data disappears. I call the consultant and all she says is that there must be a problem with my phone so I must go into a store. No word on a refund. All apps are off and the airtime and data disappear while I am driving!!! I am really getting annoyed by this, it's the 3rd time this happens at completely random times when I am not using my phone!! Is this a way for clients to get caught out? I so want to cancel my contract with Vodacom!