Vodacom - contract canceled monies still being debited - unacceptable

I'm really getting irrated with Vodacom. In November I took out a Lte contract. Vodacom could not provide the line speed as advertised and Vodacom canceled the contract. In November 25 the unit was picked up. Dec 1st a debit was taken off. I phoned Vodacom and 1 month later still no luck with the refund. To my surprise 2 Jan 26 another debit order was taken off again. I need to speak to a manager as I have no success with the consultants. This is ridiculous and I need my monies refunded that is owned.