Bad Client Service

I had a contract with Vodacom for 2years which deducted successfully for the 24months. After a while I realized it's still deducting the airtime as a debit order from my account. I phoned vodacom in December 2020 to cancel the ongoing contract I was not aware of, yet the lady I spoke to never cancelled it. They continued to deduct December 2020, January 2021, February 2021 and March 2021. I've spent almost 2hours trying to cancel the contract yet no one is cancelling the contract, rather continuously trying to upsell. They promised to get back to me, but nothing. Now I need to phone them once again with the hope of getting the contract cancelled.