Dishonest Auto Guard

I had a maintenance plan for my car at Auto Guard SA. The maintenance plan was cancelled in May 2019 but Auto Guard thought it is a good idea to still offer the debit order for 6 months following the cancellation. I fortunately managed to have the last payment reversed but Auto Guard, after numerous e-mails, stubbornly refused to pay me back the money they owe me. I am really fed up with Auto Guard SA.