Given the very short timeframe you have before departure, I would suggest you if you have the possibility to show at the airport you are due to fly from if you can and talk directly to the QR reservation desk agent. You may not want to be considered as a no-show for your ticket !
This is what I did this monday (although, not on QR but BA/AA) when I wanted to move a JFK-LHR flight for an earlier departure. The airport sales agent can do those things most of times as they should have received instructions from the head office. I tried to call multiple times but I wouls still be holding on the phone right now if I would not have decided to get to the airport !