Originally Posted by
BinSabai
thanks for this Thai-Kiwi
did you also check upgradability of biz class fares to F?
Just for you (and everybody else!) I had a look, and indeed there are some J fares that are not necessarily able to be GUP/PUP to first class.
I found an 'Early Silk Saver' J fare CDG-BKK with the following note on GUP/PUP "permitted except for promotional fares. Contact THAI office". The same note was also on the Royal Silk Plus fare...
The Early Silk Saver fare was EUR 2600, and the Royal SIlk Plus fare was EUR3400. Not sure how low a promotional J fare would need to be below the EarlySaver.