unauthorized debi check

I app**** for policies online with old mutual hoping that I will receive a call regarding my application to give them my start date request, old mutual debited my account using a Debi check mandate meaning it cannot be reversed by my bank but who authorized it because I didn't give them my consent and as a financial institute they should've communicated with me and gotten my consent. I tried sending emails, i tried calling them with no luck, such poor service!!! i want my funds refunded!!!