Yes Princess does do this as a wait-list to move you up. Brings you more to the top than others who did not put up any money and just hoped on a GTY or asked to be put on the wait-list. We have done it before.
There is all sort of game playing when it comes to this.
Hopefully you used a credit card and not cash. If you do not get your wait-list they will credit you, but it takes sometime.
And as Lisa said it is usually when final payment is due when these cabins become available. Normally about a week after final payment. Keep in contact with your TA at final payment.
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