I'm sure everyone has had problems from time to time, it's a shame the first manager was so rude, after all you had confirmation numbers. Glad it was resolved to your satisfaction.
The only problem we had with Delta was several years ago. We had met friends in Orlando, and we were all supposed to be on the same flight from MCO to ATL, then we were flying on to SAT, and they to LAX. Well, our MCO to ATL flight was cancelled, and they re-routed us to DFW and our friends were on the next flight to ATL...not a big problem, but we had to check in and redo the tickets.
Mom had hip replacement about 2 months earlier, and it was uncomfortable for her to wait in the long line. One manager saw this, and told us to wait at the line exit, and the next agent would be with us. While we were waiting, another Delta employee asked why we were waiting there. We explained and this guy just went off on us, saying we had to wait through the line like everybody else...which was now LONGER, and made us move, treating us like 'bad children'. The ticket agent caught this out of the corner of his eye, and when we finally got to his window he apologized and said he would report the incident. He upgraded us ALL to first class all the way through. And we'd gotten really cheap tickets, $114 round trip, so it worked out well anyway. We fly Delta now whenever we can.
Don't get me started on American Airlines, though...