Movie Rental on iPad

i have downloaded two films on the ipad, when i go to watch them in my videos they say that i have rented the items but not downloaded them. when i go onto itunes to try and download them, they are no where to be seen. Also when i search the items on itunes, it gives me the option to watch them and then again the problem is that I havent downloaded them?

this is driving me insane can anyone help? I have paid for these rentals! biggest waste of £10 ever.