Final update from me. Just before the 60-day DOT deadline, TAP refunded the ticket less $1100 in fees. Interestingly they had told me they were going to refund by wire transfer, but it came back by credit card.

I did write to the DOT begging them to take real action against TAP given their awful track record on refunds. Unfortunately it looks like the DOT have their own capacity problems due to all the complaints they are getting (about TAP )

estrela It would have been fun to impound one of their aircraft - someone I knew once did that to the Eurostar, but I've got $6500 back out of $7600, the wife is happy, and life is too short to continue the fight!

Moral of the story: file a DOT complaint early.