I've had a similar situation happen using Paypal. It was for a merchandise purchase, not airfare. But the charge just got stuck in "pending " in Paypal. As you found, there was no way to address this with Paypal.
As you did, I contacted the seller, who had no record of the purchase.
After 48 hours, I just repurchased and figured I'd deal with the dispute if I got double charged, but the original "pending" sale just went away and never dropped to my card, nor did I receive a double shipment. I think if the seller doesn't complete the sale, it's voided (after xx days?) I believe Paypal is a passive conduit - they simply record the purchase, hold it as pending until they receive a "purchase order" from the seller and remit funds from your authorized account. It's more a checkout convenience than anything else, though they offer some protections, most esp. when the vendor only accepts Paypal.
My Paypal account is linked to a credit card, not a debit card, so there was no overdraw danger in my case.
Triple check with AA. If they have no record of your purchase or PNR, and your bank shows nothing debited, and you want to travel...buy again.
Three things -
- write down PNRs and conf. numbers, don't count on emails
- pay with a credit card, so you aren't tying up your liquidity.
- classic French mayonnaise is to Miracle Whip as hand-tooled leather is to Naugahyde.