Vodacom deducted debit order after contract end date

We dad a business data contract with Vodacom VB028006-2 which has come to an end. I have emailed numerous times to stop this contract and debit order. I have received emails from Vodacom to state issue has been resolved and finalized. This is not the case. I want the last 6 months over deducted to be refunded to us. We even went into a Vodacom store twice they were unable to assist apparently cancellations can only be done telephonically or online. Contact me URGENT once the refund has been processed Thank you