Here is what I do if they pull this scam on me and refuse to void the transacton, not credit it. I circle the local currency amount. cross out the statement that I accept the conversion as final and write local currency not offered. I then will most assuredly dispute the bill and insist on a charge back If people began to do this, it might slow this cancer down.
I have noticed that it is becoming more prevelent in countries where it was never used before. Of course the scam originated in Ireland (so it's no surprise you had to deal with an Irish company) and had spread to Spain and Italy. It was also pulled on me in Scotland and Northern Ireland. This time around, a hotel I had stayed at for years tried to pull it on me and a Burger King in Dublin pulled it on me and refused to re-do the transaction properly in euro. The problem in Ireland was further complicated because the so called manager was one of those many eu citizen from Eastern Europe who work in many places in the UK and Ireland and whose English is somewhat limited (but eu regs allow them to seek employment). I did exactly what I indicated above and when I got home, I disputed the charge and asked that it be charged back. The rate on that day was $1.41 to the euro and they charged me $1.52. What gall.
I trust the issue will be properly resolved.