They charged me three times -twice in euro, once in sterling, they cancelled the transactions themselves but I still lost out after the exchange rate on the refund - I contacted my visa provider and they refunded the exchange rate difference.
I think you should get onto your visa provider anyway - I'm sure, like me, you haven't been provided with a receipt or terms and conditions so it may be best to nip things in the bud and arrange a refund. They UK website has a big percentage cancellation fee but there was nothing on the irish website when I ordered.