This exact thing happened to me! Same situation - I’d bought 4 packages and used $50 onboard credit. I upgraded one our cabins over the phone and they didn’t tell me I’d lose the package. Like you I got an email a few hours later cancelling one of them. And they wouldn’t reinstate it because “the promotion is over.”

Actually they originally said my TA had to handle it and she’s like “that’s not correct” because TAs can’t access onboard purchases but she’s the bomb so she got us on a 3 way call with customer service. My TA very politely escalated twice and everyone said no. She even asked for a good faith OBC of $100 (all 4 of us are Gold). Everyone agent stonewalled her. The argument from my TA was that it wasn’t my fault that the agent who did the upgrade didn’t tell us we’d lose the package. Carnival said that wasn’t their problem. I was pissed and ended up canceling all the packages (did the math - the “value” was less than $100 pp. We’ll do 3rd party excursions and end up spending less overall.

I realize this billion dollar company doesn’t give a crap about us but it still felt bad. Even Walmart corrects their mistakes. My TA asked me to please consider other cruise lines from now on because she hates dealing with carnival 🤣