Now paying for 10 licences when I have only ever had 5

Somehow my renewal has gone ahead and charged my card $300 for 10 licences when the previous subscription was only for 5. I don't really need them; I could find better use for the $110 if it were refunded.  

You can contact Norton Support to ask them to help you downgrade your 360 version and have them refund the difference in price.   www.norton.com/contactcs   If using the chat function, as soon as you can enter any information, enter "agent please". That will get you out of the chat bot and connected to a human.