I guess I should post a follow up to this... after we file the price protection form...two days later Carnival responded and said they denied my claim. Luckily, my wonderful TA refiled the claim and included the faxed copy of the pricing I printed out at the time of the price drop. Carnival did not respond within 2 business days as they claim they will on their website.
When Mert went and looked at the booking all they credited was $2 and change for a drop in taxes and not the $670 they actually should have credited. Well it was Thursday and we sailed on Saturday... Mert kept working on it even after we sailed. Finally on day #4 of our cruise the credit was finally applied. Mert emailed me to let me know and it finally showed up on our onboard account.
I learned a lot... #1 if you see a lower price, print it out or do a screen shot and be able to prove it, since Carnival isn't going to honor the price drop without documentation, even if the rate was lower. #2 Book through a great TA so you have an objective 3rd party to fight for you. #3 Don't expect Carnival to reply in a timely manner and be prepared to follow up if they don't.