I know I can try the billing error route regarding the Hertz DCC billing.

However, the amount involved is less than $10 in absolute dollar. Not worth the time and effort, even for the common good, imo.

Furthermore, it does show the CORRECT GBP amount, except it used an exchange rate that is 3% higher than the prevailing rate to convert it to USD.

I am not sure this can be called billing error in a strict sense. How do you dispute the exchange rate?

There is NO opt out box to check on Hertz contract we signed at Edinburgh - and that is a Corporate location, if that means anything.

The return location is at Liverpool airport, and is a franchisee location. In fact the information on the contract about return is so vague - no description of physical location at all, just Airport terminal, gave us some worry at first - it could have been Airport terminal at any airport, right?!

Recently I bought tickets on Virgin Blue Australia, at the check-out, it does have box for you to check which type of billing you want - DCC or Local Currency. The local currency billing turned up on my Schwab card with exactly 1% padding in the conversion rate being used.