Thanks so much for that very comprehensive reply, Blackberry.
I rang up Bank of Ireland about the €75 and they connected me to the British company which offers the 'card protection' for Bank of Ireland Mastercard. The guy on the phone said that in 2006 I paid for a card protection plan for three years and did, as you suggested, tick a box allowing it to be renewed. The thing I binned was, he said, a letter allowing me to opt out of my commitment in 2006 and when that was not returned he said by default they charged my credit card.
I explained to him that I had no need for it etc, and he said I could opt out of it in 3 years time etc. By the end of the conversation he said he'd make an exception and refund the money to me.
Hard to believe such protection serves absolutely no purpose for holders of credit cards. Thanks once again.