It's quite possible agents working other flights may be unwilling to help you. You could even be unlucky enough to get one who's having a bad day (or life) and deliberately disobliges by giving you a bad seat. (I'm not saying this is endemic to Delta, it could happen anywhere).

If you haven't yet posted in the Delta forum, by all means do so. The accumulated knowledge of the airline to be had there probably outstrips the accumulated knowledge at the airline itself.

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