UPDATE:
We finally solved our Tillys problem as follows:
First, we ordered the same longboard from another company. They shipped it the next day, and we were able to watch it make the cross-country trip from the West Coast to Miami -- while we also watched the Tilly's "shipment" sit motionless in Los Angeles on the same FedEx tracking system.
It arrived today -- 6 days from order to delivery -- and it's beautiful -- so DD's Christmas is not disappointing.
Second, we called her credit card company and learned that Tillys had not even requested a credit authorization for the purchase, so obviously no dispute was necessary.
Third, we called Tillys and actually got some good customer service. They researched the order. Their records show the order "shipped," but they also show that no credit card authorization was ever made -- which is done just prior to the actual shipment.
(My suspicions retired fraud detective brain makes me wonder if someone in their fulfillment department is not marking things "shipped" but not shipping them, and then stealing and reselling the items. If they don't have good control systems, that could go undetected for quite some time.)
The solution on the Tillys end was to submit an automatic refund -- so if her card ever IS billed, a refund will automatically cancel the charge. Or so they say.
Lots of hassle, and we won't order from them again, but finally resolved.