My AmEx statement showed the charge as denominated in GBP, but the amount was around £83, so somehow the agent had put in EUR100 and the system converted it to Sterling. For some reason, the charge didn't appear to go through initially, so the agent ran the charge again, this time doing EUR100 in USD. I noticed that both charges hit my card, and @DeltaAssist put in a refund request. The agent processing the refund refunded both charges. Since this was on my AmEx plat and DL is my airline of choice, I also got $200 credited back by AmEx (that was not clawed back after the credits posted).