Thank you so much! Finally I wrote Wilka (the lock Trademark) and they send me the original instructions. I'm going to attach it to the post.

Many thanks!

Cheers.

Hi!

Thanks for the answer. I appreciate it.

I'm afraid there are only two screws in the faceplate but it seems they are to set the lock agains the door only. Anyway I removed them:

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I cleaned the lock with a driller but I dont see any other holes on it.

This is very strange.

Many thanks any way!