In my case they said once the cards were canceled they can't reactivate them anymore but I did not ask Blackhawk directly. I requested cancellation 3 weeks after order (too soon). They refunded the money to credit card 2 weeks later. The cards eventually arrived 4 weeks after I ordered them but to no use. If someone charged GCs before cancellation the case would go through fraud department and it would take longer to recover funds.
VGCs were mailed with free USPS