Cartrack false promises

On the 18th June 2018 Cartrack manager called me and ensured me that they are going to cancel arrears as it was their fault for using a different acc no. she promised me that they are going to deduct the normal installment. On the 25th of June they debited R640 instead of R250. I would like to cancel cartrack CONTRACT as they are full of stories. this is the 2nd time i'm complaining, if not resolved i'm going to take this matter up. NENE00513