Without knowing the specifics of the particular promotion you are interested in, I suspect, unfortunately, that you won't be able to take advantage of the promotion. It is worth giving Southwest Vacations a call though, just to see if there's anything they can do for you.
You should be aware that Southwest Vacations and Southwest Airlines are actually two completely different companies. Southwest Vacations is actually Mark Travel, an online travel agent doing business through a marketing agreement with Southwest Airlines. You may possibly find a good package deal through Southwest Vacations (when their promotion terms align with your travel plans), but it's worth noting that complaints about Southwest Vacations' customer service and policies that differ from Southwest Airlines are common.
Most importantly, be aware that should you have any problems with Southwest Vacations, all customer service issues will have to be dealt directly with them, and not Southwest Airlines.
