[easygoing]

Hi
first and foremost very sorry for your experience and fully understand your frustration
but unfortunately that airlines have rules in place and of course in their favour
i am not sure how many travellers understand that airlines invariablely classified eco/business classes into numurose sub-classes such as " b m k l w" ...... based on different fare rules and prices to construct their price scheme when when certain sub-class fare bucket is empted ,they close this class ,some agents simply told passenger that there is no seat available but do not explain further and that behaviour might cause some misunderstanding that traveller may think there should be no space in the principle class they travel and when get on board it turned out many seats are still empty,
obviously some agents did not clarified with traveller so they had not correlated exactly with the same booking class when they talked to each other
anyway sorry for your experience