I would not be a dork about this. Have telecentro relocate the box to a lower portion of the building that is on a surface that is not shared by anybody. Try and work this out with the consorcio / administrador if there is one. I really would do my best to avoid lawyers in this because just like in the US the one that is going to come out ahead financially in this will be the lawyer and you will be out money AND have a bunch of angry neighbors. Period.