It's not a valid dispute as being an unknown charge, but if a merchant sells you something and then won't process a legitimate refund in a timely manner, then you can/should request the assistance of your CC to get their attention. Unfortunately there are some very large merchants (like AA) that make if near impossible to do a charge-back and the CC may choose to absorb the charge.

It sounds like the agent was taking advantage of no one being available to correct them. If the OP has status and status says free baggage, then that's what they should get.