Can I prepay gratuities using a Princess Gift Card?

[tabprincess]

A rep on the Princess chat said if I want to prepay my gratuities before sailing, I have to use a credit card and then once onboard, give gift card to courtesy desk and they will credit back my credit card.  This sounds very unusual to me.  Does anyone have any experience doing this?

[milolii]

I paid mine on Friday using a gift card. There was even a balance after which I then went online and applied to my fare.  I called the vacation planner department as my CVP is off until 12/19.   Call and talk to a person.