looking of a postponed flight


Flight SU544 from Vietnam (Ho Chi Mihn) on the 27th of February for postponed for 24 hours due to technical problems.
My daughter (passenger) sent me a text message on 28th February saying that they will be taking off around 18.30h local Vietnam time and that the flight had changed to SU1544.
Neither of these flights are to be traced on Flightaware.
Any ideas what I can do to trace this flight ?
All suggestions are welcome.
Thansk in advance, Andy


I’d suggest calling Aeroflot.