I spend a lot of time in Ireland for work. As a result, I've goten DCC'd multiple times. I primarily use my Chase Sapphire Reserve credit card. I recently disputed a charge for 100 EUR and was impressed by how easy Chase made it. I logged into my account and selected the charge, then set the reason as being charged in the wrong currency. However, it said to dispute a DCC just use other. So I did and there was no option for a comment. I submitted it, and never got an email confirmation. All that happened was on my next statement, they issued a $5 refund. That $5 is quite generous given the fact that the DCC markup was 3.5%. I will definitely be disputing all DCC charges on my Chase cards from now on given how easy this entire process was.