We flew premium economy New York-Frankfurt part of a trip to Moscow. On time, efficient boarding and service. On the way back, the flight was overbooked. Instead of upgrading frequent flyers or customers, they announce open seats for premium economy and first class to general public for not a lot of euros. This did not sit right for some of us who payed regular fares. And since some travelers parties were split, as if parents and children fly in different sections, this added a lot of traffic in the cabin. This also was unpleasant. Very unpleasant.