Refund the extra money you debited. Horrible Customer Service.

I got in an accident on the 10th of Aug. On the day I called Cartrack letting them know that I won't have a car as I was in an accident. They told me the contract is 3 years and if I want to cancel it will be R2650. I asked for a payment arrangement. The agent said I could R530 for 5 months. I asked for confirmation that I will only be paying R530 and no additional cost. He said yes. Close to month end of September I receive an SMS saying that I have a payment of R530 (Reminder) as per the agreement. To my surprise I get a bank notification that R850 was debited from my account, which was strange because the agreed amount was R530? The company sent me reminder of R530 why you are taking more than we had agreed. I am asking for a refund for the extra you took. Agreement is R530 I no longer use the tracker nor have the car that I was using, I can't pay for the tracker plus the cancellation fee of R250. Highly disappointed and dissatisfied from Car track service. Kindly refund me the extra money you debited. Let's stick to the R530 we agreed on as per the discussion. Happy for call recordings to be looked at. Not happy at all.