We booked Early Savers rate for the cruise in July; before the cruise was paid off Carnival was offering upgrades for past guests. Called my PVP at Carnival & he was able to cancel the early savers rate & get me into a past guest rate (same price) but I was able to be upgraded several cat. & to another deck. Woo Hoo!! Go PVP.
I may be missing something or misunderstood as I've not heard of "canceling" the Early Saver rate to take advantage of the Past Guest rate for price reductions, OBC's, and up-decks. I've always kept the Early Saver rate and Carnival has given them to me and kept the Early Saver rate on my booking. I like keeping the Early Saver rate in case there are any more price reductions.