I went through the same thing before cruising in June. Nobody knew about the CC discount. As it turned out, I was ok not upgrading. On ship, there were so many drinks that couldn’t be made because they didn’t have lots of things. For the few drinks that we ordered that were above the classic price limit, we only paid the difference plus tip. For example on an Aperol spritz, paid $1 plus 20 cents tip. Next day, they ran out of Aperol. Don’t waste your money upgrading.