Originally Posted by
MorganB
I had to call in to get the big red D fares upgraded and have never paid a change fee. It took AGES to get it done however. Both times I have done this it took 45 minutes on the telephone. I think the agent in New Jersey has to contact the ticket desk in Jacksonville, FL to actually have the change made. It never cost me a dime beyond the points however. The last time I did this was one year ago however.
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.