Originally Posted by
FrancisA
I think you may have been lucky on this as the Big D (Sale fares) are normally cannot be upgraded either with cash or miles. Same applies to P booking class (which is an upgrade from WT).
I thought OP was referring to using a promo code to get discount (i.e. on normal or non-big D sale fare) then using miles to upgrade.
I've done it on two separate occasions with two of us traveling each time (MFU from WT+ to CW). Last time I did it there was discussion on this board about it and the official BA poster (BA ExecutiveClub) confirmed that it was possible. Both times I had to call in and it took forever but I didn't get any resistance from the agent.