UPDATE:
Let me just say that the DL Twitter team is so much more helpful than the call center. When I called Delta for my dad the other day they agreed to the change but they got a supervisors permission to change it, but for a charge of 50 dollars to take over the ticket, and the fare difference and they refused to change it to the later flight without a 200 dollar change fee, so it was going to cost over 300 dollars to change. But I sent a twitter DM for my dad and they noticed that the supervisor had documented the ticket to allow changes, so twitter team fixed and got him the later flight as well. Even got the 1 Dollar refund for the fare difference.
Thank you Delta!