Originally Posted by
VA1379
The travel credits issued for a voluntary bump are not refundable (you will lose the travel credits if you cancel your flight)
I don't believe this is correct.
VDB certs are applied as an exchange, and the ticket value is the ticket value. If you change your ticket, it still has value (less the change fee, of course).
If you use an e-cert or a CS voucher, then they reduce the fare by the amount of the ticket, and you cannot recover the amount.