I'm very heart broken about this company, they don't want to reverse payment that was unauthorise...

I'm very heart broken about this company, they don't want to reverse payment that was unauthorised by me R8250 was deducted from my bank account. I had terminated my contract with them,I gave their car back due to non payment previous month,paid the outstanding amount and as my contract was terminated, they deducted money that I don't have the car anymore. Nothing was wrong with the car,gave as I received. I was then asked if they can re open the account and not reverse this amount now,I refused. Took it up with my ABSA. Still waiting for reply from them. I don't understand why they took a extra amount of money for a car not owned by me anymore.