Unauthorized debit orders on your account

We used Norton Anti Virus since 2011. All of the sudden they just deducted R799.99 from our bank account for 'Premium Deluxe Anti Virus Package for 10 devices'. My current Norton only expires end of August and I did not authorised said upgrade/new installation. When you try and phone them, the number does not exist. Trying to chat online, they said waitin period is 4 minutes, but 15 minutes later you are still waiting.... Watch out for buying online, once they have your banking details they do what they want and hide behind unreachable numbers and online support to try and get away with unauthorized purchases.