Welcome to Cruise-Chat. Too bad you didn't find this site before your cruise. We could have helped you know what to expect with the Holiday. Buying a cruise based on price only is not wise, especially with an experienced cruiser who has set expectations.
Several of us went on the Holiday together last July. I don't recall the buffet having hamburgers and hotdogs only.
I don't know who or how you booked your cruise, but if your gratuities were pre-paid with your cruise per diem, then they can't be adjusted on the ship. If they weren't pre-paid and only placed on your Sail and Sign once you checked in for the cruise then you should have been able to adjust them. As far as $40 per person being outrageous, it isn't at all. That's only $10 a day per person and that covers your cabin attendant, waiter,asst waiter (busboy), and head waiter. They work very hard and work long hours.
Since you've already been on other cruises you already know that, so you also know $10 per day per person is the norm in the industry. One cruise line has gone to $12. The crew should not be punished by having their pay taken away because of issues with the ship.
Your comment about cancelling your Princess cruise if Carnival Cruise Lines doesn't sympathize with you doesn't make sense. Carnival Cruise Lines doesn't own Princess. Carnival Corporation and PLC is the parent company. Carnival Cruise Lines and Princess operate individually.