Well, we should score one for Marriott corporate. I sent an e-mail to the Platinum service department, and within 24 hours they sent me a simple note apologizing, thanking me for my loyalty to my Marriott, and crediting my credit card the difference between what I was quoted and what I was charged after the conversion.

I would like to see Marriott address this practice systemically, but of course I cannot complain about the resolution and must compliment them on their quick response.