In January, I booked a r/t flight from AUS to PHL, with connections both ways in SLC. It's in G, so first class but not changeable. Due to a change in my itinerary, I was able to make one free change. Thankfully, this coincided with me needing to stay in SLC on the way back to AUS. On Delta's website, I changed my flight from a r/t to an open jaw, ending in SLC. The PHL to SLC flight was in F class. I booked through, gave my credit card info, and was told the change fee had been waved due to the change in my itinerary. The reservation was confirmed, as evidenced in the screenshot I've attached. But an hour later, when I logged into the reservation, it only showed the AUS to PHL one way flight, with not return from PHL to SLC. When I called Delta, they had no record of my confirmation, told me I'd cancelled the second leg, and would have to pay 600 dollars to make it an open jaw. They agreed to reinstate my old itinerary for free, but now this means I'm going to have to skip the last segment of this flight, which I was not keen to do. Has anyone had an experience like this before - where you chose a seat and confirmed the booking on the website, only to have part of the reservation vanish? And do I have any recourse to get back on the O/J, free of cost, or do I just have to skip the last segment?