Are you still at the airport?
Also can you share any more details - the more info you (feel comfortable) sharing, the better the advice we can offer.
Things like routing, mileage redemptions, booking date, schedule changes in the interim, check in with QR (please be as detailed as possible), EXACTLY what QR said as to the why for the downgrade and the why NOT for the reroute.
Be sure to document all interactions you’ve done with QR as well. Employee names, times, etc.