Odd that, my son had exactly the same thing Brisbane-Perth last week. He's a very experienced business flyer but the turbulence was so bad he just wanted to get off. Passengers were crying etc and the TD's were strapped in for most of the flight, it lasted for 5 hours.
Apparently they were flying against an exceptional jet stream and couldn't get above FL270 otherwise they would have been virtually hovering. The return trip that evening took 3hrs 40 minutes (normally 5 and a bit hours.)
I remember flying back from Portugal in 2000 when we had the bad storms in UK. The captain came on and said we were flying against a 120 kt headwind....