Thanks for the experience! When they got rid of the
"hold" feature, they really messed up situations like this.

I am thinking that I might try to make a reservation and
use one of the non-credit-card payment options and see
if I can hold the reservation on the new flight that way.
Then maybe call the co.com support desk and see if there
is anything they can do.

I'll post here if anything good comes of it. Thanks!