last time I booked (a couple of months ago), you had to click on a link during the sale process to switch the currency back to the original ... and the link is barely highlighted - so incredibly easy to miss it.

i never thought of challenging it through the credit card company.


I had a related dispute with another airline (Monarch) - where their website didn't add a credit card fee until after I had clicked purchase (so I had no option to swap to debit card to avoid fee).
I phoned them up straight away (trying to cancel and rebook) - but they refused. And since I don't take screenshots every time I book a flight - I couldn't prove that it was a glitch in their website.