Can't stop iPad from downloading three movies

If you want to delete them from the Downloads tab in the iTunes store app then you can pause them, if you haven't already done so, by tapping on them - does tapping the Edit button top left of the screen then let you select and delete them from there ?

You could try contacting iTunes Support and see if they can remove them from your download queue : http://www.apple.com/support/itunes/contact/ - click on Contact iTunes Store Support on the right-hand side of the page

You shouldn't have to pay if you contact them via the above link

No, the iPad doesn't support that.

Doesn't support what ? My above reply was for for iOS 8, but on iOS 9 I can also tap on a film or TV programme in the Downloads tab in the iTunes Store app to pause and then use Edit to select and delete it.

If that doesn't work then see my second reply

On iOS 8.4, if you have rented a movie and it is downloading in iTunes Store, you cannot pause it (the pause button does nothing) and you cannot delete it (the Edit button brings you to another screen that does nothing). There is no swipe or other actions that can change the download other than contacting Apple and telling them to kill it and refund your money.

I assume that you talking about purchases, not rentals

No, rental. You rent them, they download and have 30 days to watch it. Once you rent, you have zero ability to control the download unless Apple Support intercedes.