Refund on the account debited (by mistake ) according to Vodacom

Vodacom are ****** with no shame. I had a contact with them and it was a nightmare for the entire 2 years of the contract, when I was finally glad that the contract was over. they debited my account even after the contract has expired and cancelled. They admitted to have debited my account by mistake but has since been promising to refund me, and then the story was changing each time I called them, I'm still waiting for my money. I have a proof of them admitting to have debited my account by mistake and also them promising to refund me within 14 days but I haven't gotten my money. 14 days turned into months now.