I replied to the letter in my email, basically stating my case again-we'll see what happens. I'll call again as well. After my flight, I'll write to HA again as the customer service email suggested. I still can't imagine they wouldn't fund the fare difference.

The last options are the DOT strategy and also, I wonder if it would work to try to dispute the charge on my credit card, although this would be long after the 60-day window the credit card companies like.