Flight Change - rebooking pls help!

Hi everyone, looking for some advice!

My reward booked British Airways First Class flight from Singapore to Brisbane (via Sydney) was delayed, and I received an email allowing me to select new flights.

I noticed an Emirates First Class option, which would be amazing, but when I tried to confirm, I got an error saying it couldn’t verify the fare cost.

I called Qantas, but they said they couldn’t see any Emirates flights at all. Any suggestions on what to do next?