What really matters are the terms under which you originally booked the reservation. Your original confirmation email should list the cancellation policy; that's what you will go by, regardless of what your reservation now says. No credit card company will uphold any penalties if you can show that you cancelled within the terms of the original reservation.

Bear in mind that even if the terms of your original reservation allow you to cancel without penalty, any modifications to your reservation might be subject to current availability and policies.