I have three transatlantic legs in the next few weeks, one T, one U and one L. I took a look at the seating situation and noticed a green panel on the left that said "Choose economy comfort at no charge on this flight".

I was surprised, but gave it a shot with the T flight and it seemed reluctant to give me an EC seat, a red error message appeared saying it was unable to allocate the seat and the original seat number stayed on my itinerary.

I tried the other trip (U and L) where the same green offer appeared and this time it gave me an EC seat first try on both legs. I went back to the other flight and tried again, choosing a different EC seat, and this time it gave me it.

So is all this just incompetent programming of the Delta reservation system and will I be expected to pay up or sit in the back when I get to the airport or have I really got EC at no extra charge on T, U and L fares?