Taiwan: one restaurant charge went through in USD despite my choice of NTD being clear (as in dddscy's example). I disputed the difference (approx. 5 USD) and Chase credited my account within minutes.
Can you give more information here? The signed receipt and your customer copy indicated [X] NTD printed thermally by the printer (not simply you checking the box yourself?
Can you name and shame the restaurant? I can investigate during my next trip. This behavior is contrary to what I've experienced in the past over dozens of DCC transactions from many acquirerers.