Something similar happened to me at a Marriott restaurant in Phuket. Without being asked, my credit card was charged in "US Dollars" instead of bahts. When I looked at the conversion rate used for that charge I realized that the transaction (slightly less than $100) cost me almost $4 because it was not charged in bahts. I asked the restaurant manager to cancel the transaction and charge me in bahts and he complied. Therefore, Never had to got to Chase to dispute the issue.