The bad news is, you have no remedy
They will argue (correctly in legal terms) that they have fully fulfilled their contract to get you from Spain to the USA and you are therefore not entitled to anything. I think you have done the only thing you can. Give them bad publicity and vow never to fly them again. The key is to mean and genuinely never fly them again. I had a bad experience with Delta over 12 years ago in Charlotte, NC and I have never flown them again. If enough people did it, it would make a difference. The problem is too many people choose only on price, and that in part drives the fight to the bottom that many airlines are on.
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