Hi cillasmum,
I have been having similar problems when trying to register for Endesa online, the site would not recognise my NIE number or UK phone number.
I used the 'Contact Us' at the top right hand side of the home page (when switched to english) and then the 'Contact Form' where I explained that the online office would not accept my details.
This was monday evening and yesterday I received an email informing me of the following;
In order to help you, we have filled the form for you and these are your login details:
USER/USARIO
PASSWORD/CLAVE
Once you get the access, you should change both user and password and activate the electronic invoice.
If you want to activate the electronic invoice, please access you online account and choose on the left side the option Bills and Sign up for service and click to Complete Activation. If you sign up for this service, you will no longer receive paper bills.
Also you need to know that the information of your Endesa Online account will be available in about 24/48 hours.
Thank you for using our Online Office.
Obviously I have removed the user and password they gave me and tonight I have accessed the Online Office for the first time, changed my password and signed up for electronic billing no problems at all.
Hope this helps.
kelju