Cannot change country, previous rental unexpired

HI

IPad 2 with IOS 6

2 months ago while living in the US I rented a film but did not finish downloading it before I returned to the UK. My Apple ID was registered in the US at the time. Since returning permanently to the UK (more than 40 days ago now) I have changed my Apple ID region, address and payment details to the UK successfully. However, since then I have had problems using my Apple ID as it still says I am still accessing the US store and to change country. When I try to change country now it says "you have rentals that have not expired" and will not let me even view what country my Apple ID is registered to. The previous rental, if that is the problem, does not show anywhere inside my iTunes store and so I cannot delete it. Any help appreciated.