Got a reply from Avis Sweden:
Thank you for your mail!
You were originally charged in USD. In order for the charge to go through to your
creditcard issued in Sweden the charge had to be converted from USD to SKR.
Avis customers are charged in the currency of country of residence.
That you were not asked is because you are a preferred customer and have a “signature on file”.
If you at a future rental would like to be charged in the currency of the country where you rent
you need only to say so when picking up the car, and sign for it.
I hope I could answer your question.
That is hopeless. I was never given a choice nor I have agreed or signed anything that I'll be billed in SEK. The most annoying part is that I have to say it and sign something that is supposed to be the norm. I have
never given a choice to opt out DCC.
I have sent them a last e-mail giving them either 1. readjust the bill back to USD or 2. refund the DCC charge.
If they turn me down, I'm definitely going for a charge back