I have been on text messages with DL for over an hour. I gave them the flight details and explained that the DL system only showed REP (which has been closed for almost 2 years), and expanded to show nearby airport which then SAI showed. The agent confirmed she found it, and was about to book it. But then she came back asking if SAI was in Italy because that what the system showed! I explained SAI in Cambodia. In the end I gave up. Now have DL miles which cannot be used at all on VN ☹️ - frustrating.