It seems like one of those things that are a foregone conclusion, but that's the danger of assumptions.
Recently, we tackled the issue of getting refunds when the original transaction was in a foreign currency. Do you get or lose the difference? Quite mistakenly, it seemed like any amount difference due to forex differences was lost and forever gone. It turns out we were quite wrong.
On a recent chat with the bank (about another delivery snafu!), the bank representative on the phone elucidated that we could dispute the transaction differences.
So there it goes: Based on principles, how much do you want that money back?