Call them and check-here is my experience with easy numbers used for example purposes.
Charged $1500 for trip. Then had other monthly misc. charges for $1,000. I thought I only had to pay the 1,000 for other the charges b/c the trip charge should be 0% interest for 6 months. Well, I got charged interest. I called them and was told I had to pay the monthly minimum in addition to the extra charges to receive no interest due. I guess you just have 6 months to pay it off interest free, but have to pay a minimum every month on the vacation charges. Once, I sent payment for my monthly misc. charges + the minimum payment, I no longer received interest charges.