Double charged and changing exchange rate?

[UtterlyUnimaginativeUsername]

I paid in euro for an activity we're going to do on holidays. The company accidentally charged me twice. I informed them, they looked into it and refunded me one payment.

However, in the three weeks it took to deal with the issue, the exchange rate had dropped. When they charged me, they took the equivalent of €107 twice, but when they refunded me one of those, I only got €82 back.

Should I ask them to reimburse me for the difference? The overcharging was their error and now I'm out of pocket by €25.

Though thinking about it, the dropping exchange rate means our money will go a lot further while we're there, so we'll benefit by more than €25. I think I'll just leave it.