Originally Posted by
Mabuk dan gila
If you had a valid, ticketed, onward itinerary to show them, Delta is UNCONDITIONALLY wrong and 100% to blame. Raise hell, write letters, demand compensation. There is no gray area if you presented a valid, ticketed, onward itinerary. They flat out were in the wrong. I would have escalated it as high as possible by any means possible on the spot.
The OP never said he offered to show proof or showed this to Delta. Can you please clarify OP?