Originally Posted by
DTW-HomeyFour
B-fares are not all equal. Some B-fares are B-UP, booking into F. Some B fares are also refundable, while some are not. Best to check the individual fare rules.
You're talking about something different than an E-First upgrade. E-First upgrades are offered through the kiosks or sometimes OLCI for a fee. I don't know if there are fare class restrictions for E-First upgrades; but it's one of things that you should try asking the GA about next time, rather than the elite line.
There was a thread about this earlier. A search might bring up some useful information.