Hopefully they fix the issues before your Oct flight.
I was scheduled for DL446 back on Sept 6. JFK-BOM
On Sept 3rd, I got a notification from Delta that my flight had been cancelled. I called the DM line and the rep contacted Operations and said everything looked fine. The next day (4th) the delta app and online showed my flights as cancelled. I called DM line again, and the response was the same. Then 1 day prior, I could not check-in and the app and online was giving me alternate flights to choose from. I contacted DM line because the flight still showed cancelled. First rep said flight was cancelled and best they could do was to route me via CDG and I would now get there a day late. I said hold on and chose to do some more checking before having it changed. The app was giving me an option via BOS that connected in AMS on DL148 to BOM. Yet the Delta rep could not find anything on that flight number (turns out it was some temp number assigned to the AMS-BOM leg but shows no history in the systems).
I finally called the DM line back and spent 40 mins fixing my reservation (now via BOS-AMS-BOM rather than DL446 JFK-AMS-BOM). What sucks is that the BOS-AMS leg had no economy comfort seats left, but at least I did not sit in a middle. I was told the JFK-AMS leg had been cancelled and the AMS-BOM was now operating as DL148 (at least on Sept 7th)

End result, this change has screwed up their reservations and yet while Delta notified me days in advance, no rep could figure it out. I end up with a sub-optimal seat (compared to my DL446 one I had reserved for weeks). Hopefully the reps know how to address it now. I don't know how full AMS-BOM normally is on a Sunday, but our flight was quite empty - guessing others did not get their reservations moved to DL148.

Good Luck!