No, that does not sound right. The CVP is Exactly the one who should help you!
They work for PCL, who made the errors.
I’d call the CVP back and tell them, you need them to sort this out.
Since this was a GTY rate, is the deposit non refundable? Sounds like the agent put in the mini suite cabin and called guest services to see if they would honor the mini suite, and instead of ignoring the transaction with the mini suite, they ended the record, which booked the mini suite cabin.
The CVP should be able to check the history on this record and straighten it out. They may not have midship open right now, they should put you back to GTY and honor the midship category later then.
Are you sure the category of balcony that you chose is only midship and not
other decks or areas? You can look at the deck plans and check the decks that would be available in the category you paid. You probably did already, but to be sure.