28 Dec 2012 2:58 PM:
Excuse me resurrecting this old thread but I wanted to add some information for anyone who might find it via Google like I did.
You can enter your NIE but you have to select the option titled "Card" (if you're using the English version of the form).
Also! According to someone I spoke to at Endesa, *if the bill is in your name* you have to choose 'owner'/'propitario' in the radio boxes before the form is shown, even if you're a tenant. Otherwise it'll tell you there's no account in your name.
Hope that helps someone.
Thread:
Endesa Online help
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