JQ seemed to have lots of issues with that flight when my GF was travelling back to Germany in September last year and Jetstar gave me one of the worst experiences I have ever seen (Tickets booked with AirFrance).
The original itinerary was
MEL>SIN (QF), SIN > CDG (AF), and CDG > FRA (AF). But AirFrance changed the itinerary from Qantas to Jetstar about a month before travel, When we called AirFrance about the issue they were generally apologetic and moved her into business class for the first leg.
The real issues start the night before when she gets an email saying that the Jetstar flight will be 3 hours delayed (Departing 1500 rather than 1200), No problem she has a 7-hour layover in Singapore all is good.
We check out of the airport hotel as late as we can and end up at the airport 4 hours early Jetstar checks her in give her a food voucher and then looks at the printed-out boarding pass and says there is an issue with it and reprints it to move her out of business class (she did not realize this until after she boarded the plane).
I leave her at immigration pay my parking and headed home I track her flight leaving 30 minutes early (turns out this was the JQ flight from the day before that was 27 hours delayed). at 2130 I get a message from her saying that they are deplaneng after having sat in the plane the whole time and moved the flight to the next day. I drive to the airport to help her out / possibly pick her up and get there at 2330 and she is still waiting in the queue and has been messaging Air France support who are very confused because they think she is in Singapore since a Jetstar flight just landed and her flight is technically not cancelled.
Finally, we get to the front of the line and after arguing with them about a few things (No it's just her on this flight I'm here, because she doesn't speak English perfectly and has a fear of flying, No you can't deny her a hotel because she "has somewhere to stay in Melbourne" I live 2.5 hours away from the airport at the moment and you want her to be back at the airport in 7 hours) and we are told to go to the holiday inn. we go to the holiday inn and wait in queue for half an hour and they run out of rooms.
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It's 0030 and we are sitting in my car in the holiday inn parking lot. Air Frances Australia support closes at 1900 because famously ticketing issues only happen during business hours...... but I'm able to use my US phone number to get through to their US support line and after some initial confusion as to why she is not in Singapore the support agent checks her out of the Jetstar flight and puts her on the 0530 emirates flight a few minutes later the new flights show up in the AirFrance app and we decide to just wait in the car for the 3 hours until check-in opens for the EK flight.
Once the EK flights check-in opens we head down EK support desk to make sure the ticket is all good and they can't find it.... it also disappeared in AirFrance app
30 minutes on hold with AirFrance support later and it turns out that Jetstar re-checked her into the original flight and removed her from the EK flight. they also locked the booking down so AirFrance couldn't change it another 30 minutes on hold and they issue her with a whole different booking on a separate PNR number with 20 minutes until check-in closes she gets checked in and is finally on her way.
Hmm, this is a long post, but take it as a cautionary tale.