A travel quite a lot and when a connection is cancelled, they'll generally rebook you and you can go online and change to another flight without paying a fare difference.
Just some questions, did you book your flights yourself or go through a TA? Was the NY to Barcelona flight booked on Delta? When you say "Delta as well, and got nothing", sounds like they didn't automatically rebook you, so you informed them your flight got cancelled and they came back with nothing, no offer to put you on the next flight?