I believe CruiseDeals.com is a legit site as well, are they not? I didn't say not to use VacationstoGo, I said to check CruiseDeals.com first.
Also, speaking of customer service, would it not have been a great goodwill gesture on VTG's part to say, "Hey, we do pride ourselves on having the best price. Even though it was your mistake, we're going to honor the better price and hope you'll spread the word," which I would have.
As I've often heard said about the restaurant business. "If the food is good, your customers will tell two people. If the food is bad, they'll tell 10."