Originally Posted by
Hannibal Lecter
Unfortunately that doesn't help, I picked up a car in London and even though
I had made sure to uncheck that box I got a contract which said that
I had choosen to pay in local currency 
Paying in local currency is
avoidance of DCC.
DCC is paying
in your own currency.
So it seems like it
did help!
(Or else you wrote up something other than what the contract says.
)