A friend picked up some foreign currency for me and they gave him the wrong exchange rate, thinking it was a different currency. Now they want the money back that they overpaid, and are asking for my bank details. Do I have to pay them back?
Probably. If you were unaware of the mistake and spent the money, relying on the bureau’s calculations, you might have a defence against the bank or bureau on the basis that you were worse off because of their error. Unless the amount involved was substantial they may not pursue it very far.