Originally Posted by dark_phoenix

Only credit credit cards or points AFAIK with the bidding process. The decision-making on who wins a bid may be a bit manual, but the payment once the decision is made is instant and automatic. If the payment fails for any reason they cancel your winning bid and just give it to the next person. There is no chance to contact them about it. I think that process would make trying to call and give them a voucher difficult.

Although that would be a great idea if they allowed you to enter a voucher number as a payment option someday.

You can always call or use the chat function to see if they now allow vouchers, but they didn't as of Nov 2023.