Joanne
If you want the reservation to last longer than 24/48 hours you will work for it.
I needed to get a return flight for a visa application to an African country. The reservation lasted about 24 hours and I kept having to check and send them mails to say that the reservation had disappeared/was cancelled. Now if it weren't for covid and getting money back from airlines being so complex I would have bought a refundable ticket and saved myself the job of checking if they would do theirs. To be fair they quickly rebooked it every time I reminded them that it was down. But what a hassle, and had I been going to a more rigorous country it would have given me piles.
Response from OneWayFly : Flight Reservation For VisaMar 16, 2021
Hello Joanne, We are really sorry for the inconvenience caused. As mentioned on our website the 14 days validity could only be guaranteed if the date of departure chosen is in at least +30 days. You've ordered a flight reservation for the 1st of February with a date of departure for the 19th of February. When the date of departure is so close, flights could be automatically canceled due to different reasons: overbooking, flight cancellation due to covid situation, etc. Nevertheless, someone from the support team was always present to help and I'm glad to read you've managed to get your visa. By the way, embassies usually never refuse an application because the flight ticket is not confirmed anymore. They will request you to re-submit the reservation. In any case, I hope we can serve you better next time.