This just happened to me by Avis.
I hate DCC. Earlier in the year, I rented a car in Toronto and was charged in USD instead of Canadian. That is when I found out about the "check box" in my wizard profile, which I promptly unchecked.
Subsequent rentals in Toronto have gone ok and I was charged in Canadian.
But that wasn't the case last month with a rental in France. Returned the car to CDG airport and was given a receipt showing I paid in Euro. No mention of any DCC, or me being given a choice. No mention of USD anywhere. I was pleased.
Imagine my surprise to see the charge post anyway in USD. Went online to my Avis profile and receipt is still in Euro. In this case the local Avis manager must have done the change manually.
I am disputing it with Avis (on my 4th email) and with Visa.
This is a scam and has to stop!