This has little to do with the question at hand, but we showed up with 1 table for 6 booked, and 1 table for 1 booked, and asked if we'd be able to combine them into a table for 7, and they were very friendly and accommodating about it. Gave us a table for 7 with no fuss or issues whatsoever.
Had they said no, my dad was prepared to eat alone so no huge issue, but my overall point is, these things happen, and I imagine they have minor issues like this on a daily basis... and in my experience they seemed very friendly and accommodating.
I know at most non pre-paid ADR locations, they won't charge you any fee if your party shows up 1 short... they mostly just care that you don't skip out on the reservation entirely. Since you pre-pay at CRT... your mileage may vary, but as others have said, i'd think they'd probably help you w/ a refund. (No guarantee though).