I had downloaded a rented movie from iTunes, then did a iTunes update and lost the lot due to some error. Had to restore iPad and now don't have rented movie. Where can I find it and how can I download again without having to pay for another rental?

Hello TrevTrek,

Thank you for the details of the issue you experienced with your movie rental. If you never had a chance to watch your movie, I recommend following these steps to report this to the iTunes Store:

To report an issue with your iTunes Store, App Store, Mac App Store, or iBookstore purchase, follow these steps:

1. Find the email receipt for your purchase.
2. Click Report a Problem under the app that is having the issue.
3. When prompted, enter the Apple ID and password you used to purchase the item, then click Report a Problem.
4. Click Report a Problem next to the item you are having an issue with.
5. From the Choose Problem dropdown menu, choose the appropriate issue.
6. Follow the onscreen instructions and—if prompted—type a description of the problem into the text field.
7. Click Submit to have your issue reviewed.

You can find the full article here:

How to report an issue with your iTunes Store, App Store, Mac App Store, or iBookstore purchase

http://support.apple.com/kb/ht1933

Thank you for posting in the Apple Support Communities.

Best,

Sheila M.