You don’t say who booked this. If you booked with a CVP or TA, you should call them to change it. If you booked directly, then Princess has to change it. You cannot change it yourself online.
It must match your passport, just as your flights must match your government issued ID.
I would try calling again and pick the option Ocean Ready and insist speaking to a supervisor. You may get a competent agent.
Or, you could try email for customer relations. Explain to them everything you’ve done so far.
Call when they first open on a weekday, 0600 Pacific time. Not on the weekend.
Let us know.
The IT email if you want to try it:
askoceanmedallion@carnival.com