Vodacom inefficiency or theft?

When I left SA Vodacom offered me a service allowing you to keep your SA number but use it as a pay as you go number. This seemed get for visits back. We I arrived back in SA 3 months later the number had been cancelled. (2016) It no longer exists. I am still paying R76 per month. I have spent many hours in Vodacom stores and on the phone from the UK. Everyone says they can see I have no account with Vodacom but still I pay. I tried cancelling the DO but once this reached the bank’s limit of R200 the whole amount was paid again. Anyone leaving SA do not use this Vodacom service.