Paid up, refund and ownership documents

My wife and I financed our Audi A3 through Wesbank, worst mistake ever. We settled our car and this company went to debit monthly installment even though the vehicle has been paid up. We called and they promised to refund us our money within 7 working days. I'm not sure how they count their days but it's been over 28 working and they are still giving us a run around. When ask them why they continue debiting our account even the vehicle was paid, they said it was a system error. Just like that, a system error that can't sorted out even today. Please rectify this today