Yes, you have to prepay for CRT. I'm not on the
DDP, but my notes sayyou still have to prepay for it, and then you receive a credit back to your card when you arrive and present your DDP (this was last spring when I was taking notes considering the DDP).
They charged my credit card for the entire amount plus a mandatory gratuity a day or two after I made the ADR. I had an AP voucher and they said that when I arrive to simply present my activated AP and they'd credit me back the difference. We go on the 31st so I can't report on how smoothly that went yet. You have to cancel 48 hours in advance to receive a refund.
I was also required to give a credit card number for Akershus....but nothing was charged. I was told that if we failed to show we'd be charged $10 per person to that credit card. My notes say 48 hour cancellation for this as well.
For the BBB I was also required to give a credit card and will be charged $10 for each appointment if we don't show. This one has a 24 hour cancellation requirement.
There may be others that require a credit card as security....these are just the ones that we did.