I am in Australia and trying to renew my map subscription. When I go to the checkout screen the 'Country' field is displaying United Kingdom and is greyed out so I can't change it. I enter Australia in the 'Country of residence' and 'Country confirm' fields and I fill in my address details including my postcode in Australia. When I accept terms and conditions and click Continue the Postcode field is highlighted with the message 'Please enter a postcode'. I believe the form is expecting a UK postcode and this prevents me from proceeding with my order. How can I change the Country so that the form will accept an Australian postcode?