I dont think this is just a Thomas Cook thing. We flew with Thomson in May, my daughter and myself booked together, my husband booked later as his was just a return flight from Dalaman and when we asked to be seated together we were told the seats were already allocated. Ater getting the THomson rep involved who requested we get seats together if there were free seats available, we were seated together. When we get on the plane the six or seven rows in front of us on both sides were empty. Not sure why all the fuss was made by the check in staff at Dalaman but that seems to be the norm with them.