Still got the problem - my Spanish bank account was temporarily unfrozen but now frozen again. This is down to the same issue: they want me to prove I don't live in Spain and so am entitled to a non-resident bank account. This is something you can't do without actually being in Spain and going to the Ministry of the Interior - try finding a way in the UK of proving you live here and not in Spain!
The online Endesa service is no good for me as it requires a Spanish phone number and 2 surnames (ie a Spanish name). Crazy, because the site is in English but does not accept English details. There is a quick bill payment option on their website but I can't use it, because the details on my bill are for a direct debit and can't be entered on this system.
I am still trying to find a way to contact Endesa but they don't make it easy by having no numbers you can dial from the UK. No wonder Spain is in the economic mess it is in, given the level of pointless bureaucracy.
Do you have a solicitor in Spain? i ask because isn't it about time you did something constructive about this...Like going to your / a solicitor in the country you have to pay the bills in, it's been almost 4 months now since you first posted with these problems and it seems you are getting nowhere fast, except maybe more frustrated and in deeper trouble, in the least then you "Should" know it's going to be done legally and safe, if you do have a solicitor now who's doing this....Dump them for a proper one.
It's got to be the easiest way ever to prove you don't live in Spain, i didn't live in Spain and it must have been proved by me, or in other words my solicitor did, how simple is that? and i have never ever had a problem paying bills, talking to solicitor, paying taxes or anything else that other posters seem to get on her.
My solicitor even has access and delves into our bank account to know we have the money in it to pay the bills, as and when.