I rented a movie in SD and wanted HD, can I change this?
I rented a movie and received the SD version when I wanted the HD version. Can I change this or upgrade to the HD with a discount?
Purchases (including rentals) are considered final but you could try the 'report a problem' page to contact iTunes Support and see if they will refund you as a one-off so you can have a go at renting the correct version : http://reportaproblem.apple.com
Or you can try contacting iTunes Support via : http://www.apple.com/support/itunes/ww