With those "seat numbers" upstairs, are you sure you are not on one of the horrific 2 cabin 747s? In which case you are actually in F (but may have a C fare). In those they shove 6 rows into the nosecone (where there are usually 4 F rows, the same 4 rows on the upper deck (miraculously now called F) and then over 400 seats in Y. Or you may have a reconfigured 200 that used to have the 36 seat F cabin. In any event don't be surprised if you have your aircraft changed to a 400, as the 200s are always having mechanicals, and the 400s aren't being used as much on their intended routings due to decreased asia service. In any case, go UPSTAIRS!