@Anonymous User when you say it won't process, do you get an error message?
Try a different browser.
For the address where the card is registered enter 3 digits for your house number ie enter 67 as 067
Ensure your bank card is a UK bank and not a prepaid card.
You must have a minimum balance of 10p available as NowTV will do a reserve for that amount. They don't actually take the money but use it to check the account is real.