Short story:
My friend got double-charged ($30 x 2) due to kiosk (and agent?) error at the airport. We're about to try getting one of the $30 charges refunded, and need some guidance.

Long story:
Had a friend visiting me recently, she flew in on AA using points. When I took her back to the airport to return home, she needed to check a bag. We used an AA kiosk at the airport, indicated we needed to check a bag, inserted her debit card, and everything was going smoothly up to this point. When it came time to print the boarding pass and bag tag, no bag tag came out. It did print the boarding pass, along with a separate slip stating Unfortunately, we are unable to fulfill your request. It also had some codes on the bottom indicating GB error SDS.

The slip advised to see an agent for assistance. We did, and told him what happened, and showed the error slip. (My friend had already checked her bank account at this point and found a $30 pre-authorization from American, prior to approaching the agent). Of course, as a pre-authorization, we couldn't be sure if it would go through or not, because of the error at the kiosk. The agent looked at it, said it had not gone through, then took her debit card and charged it again. And after he did this, he decided to take a look at it again, and then said she had been charged the first time. Of course, this was a busy airport check-in counter with plenty of people waiting behind us, and he advised we would need to seek a refund and to hang onto the papers we had for doing that.

Both $30 charges remain on her bank account now (a week later.) I looked at the refunds section of the AA website before writing this. It seems to be focused on ticket refunds, not ancillary charges (but maybe that comes later, deeper than I dove?)

So I'm just looking for some advice on how to seek this refund, along with typical time frames for seeing the refund hit her bank once it is submitted to American.

Thanks for any help you can offer!