I finally got a BA agent on the phone Monday afternoon and was able to cancel the unused return flight, but she said she could only refund the tax on the ticket -- $5 -- and not the Avios. She gave the the AA customer service fax number as the only AA contact.

(As platbrownguy said, I only mention our household Avios supply to make the point that the 9,000 Avios is not that big of a loss. No offense intended.)

Globalizer, I have a scan of my ticket receipt that I'd be delighted to email you. As to my "plenty of seats" claim, at boarding the gate agent announced that they were opening the flight to folks holding tickets for the next flight. Even so they did not fill every seat on that small plane.

As a first-order response, I plan to dump our BA Visa in favor of a Chase Sapphire card, and avoid AA in the future. Any more constructive ideas?