I would have done the following

1) Used a travel agent, that has a relationship with AA. Travel agents have the ability to refund directly from their computers effectively bypassing American Airlines. When COVID struck, Swiss ( my national flag carrier) was among the first to remove this feature, along with the rest of Lufhansa Group.

2) Never accepted vouchers. Since you live in the US, you should not have to, since the Department of Transportation mandateed that material changes in flights need to be refunded.

3) The agent is correct, vouchers cannot be used for add collect ( i.e difference in fare) because the voucher's value is held by the ticket number. There are ways around this but a phone agent at a call center is not going to help you jump hoops to do this.


Cut your losses and ask American Airlines for your money back. When RONA is over, rebook. As for the voucher - well use that for the next American Airlines trip.