Thanks a lot, nuttyrotor!!!
The issue with your first advice is that if I go to New Zealand and then I find a good school, after that I have to come back to Spain to arrange my student visa (as in the NZ embassy told me). Thatīs the reason I would like to find the school from here.
I have sent emails to Ardmore (no answer yet) and to Garden City (they answer they do not take internacional students... I supose is what you said: they arenīt a NZQA accredited company) I pray that is not the case of Ardmore but I am afraid this is only a wishfully thinking...
I saw Wanaka has in its website a special place for international students, and the same has Helipro.
Wanaka is a bit far away and in the south where other people told me the weather (and the posibilities for flight days) is worse than in other places as in Christchurch and, specially, in Auckland. Also I thought to live in a big city (ok, not as big as Madrid, but at least as Christchurch) Probably going to Wanaka it is too much for me, so isolated.
Finally it seems that events lead me to Helipro and I am not convinced about them, despiting the trust acount they have (as Te kahu said.) I have to think about it. Fortunatly I have the money and I dont need to take a loan. Even if they have a trust acount I would prefer not to pay up front.
thanks again to everybody!