Hi guys

i had 2 reservations with this great price

one with AF,
BUD AMS SEA SFO CDG AMS BUD
in September modified for june 2021 by AF messenger with I class reservation ; its booked.

one with DL,
BUD AMS CDG (october) / CDG JFK (december) / DCA DTW LAS / LAX CDG / CDG AMS BUD (january)
Flights BUD AMS CDG in october are modified by VIE because the hungarians borders are close
it was difficult to change but i explained the borders... by iMessage with Delta

For all of my flights of, i see a schedule modification and LAX CDG is cancelled (by AF).

Now i contact Delta by iMessage to change the rest of my reservation.
It was really difficult. I flew the first segment by VIE.
I would like to change my flights in september 2021. I used ITA to see flights with DL I class booking.
I spoke during 2 hours (!!!) with a representative and then a Ticketing Support representative.
She said : i can change without repricing only before 31 March 2021, because the fare will not work after 31Mar2021...
"Changing by a day or two is possible because your flight is cancelled.. you are trying to change by 10 months.."
The repricing is not a good thing.

I'm really surprised that I couldn't change to september...

Do you know how can i do it ?
A refund is possible but i lost my great price...