We just paid off our cruise with 5 $500 ecards from AARP. We tried applying them through the Carnival website. It said the payment went through, but after waiting a couple of hours, the website didn't reflect payment. We gave Carnival a call and they did not show any payment and after checking the ecards, they still showed the full amount. The Carnival rep applied all the ecards for us. She said they were having issues with the website taking payments. So when applying ecards or the traditional cards, keep an eye on it to make sure the payments go through.