RFS bookings are not changeable within 24 hours of departure.
There have been a few reports of exceptions being made and I recall one post where QR were kind enough to reroute a person in a similar position from DOH to LHR instead of OSL but they are exceptions and shouldn't be relied upon to solve a problem that arises.
The problem you highlight is the big draw back of ex-EU bookings and the associated positioning flights.