I did not board the NRT to BOS flight because the earlier flight was diverted to KIX due to bad weather. Nevertheless, the way Japan Airlines handled the situation was extremely disappointing. The new flight (KIX-LAX-BOS) was booked without first getting consent from the passengers. I wanted to take the NRT-BOS the next day, Japan Airline ground crew told me that I needed to purchase a new ticket or May for that change. When I agreed to take the alternative flight arrangements by JAL, the ground crew was unable to advise on the proper procedures to transfer to the new flight. They initially advised me to go through immigration and pick-up my luggage (which was originally checked through all the way to Boston) and re-check in. I had to in turn told JAL staff that that is not the proper procedure and I should go through international transfer at the airport and not go through immigration and also the luggage should be routed to the new flight and I should not collect it at the transit airport. This shows the INCOMPETENCY of JAL’s ground staff at KIX. Very extremely disappointing. When I was about to board the KIX-LAX flight, JAL downgraded my seat from Premium Economy to Economy!!! I insisted that I am given my premium economy seat and after 30mins only then they are willing to do so. Has the level of customer service of JAL deteriorated that much where they can’t practice common sense and courtesy to atleast maintain the seat class. When I boarded the plane, there were still 4 empty premium economy seats. Why did they downgraded my seat?!! Just to make my life difficult? Nevertheless, my LAX-BOS was downgraded to economy. I would like to know how JAL plans to compensate this downgrade! Is this JAL bullying their passengers? I demand an explanation from JAL.