As an aside - I know it’s a bit old fashioned, but I presume it’s still acceptable for a married woman to be called Mrs John Smith, if her husbands name is John Smith. It’s probably used in writing (such as on your Éir account), rather than in conversation. But I wouldn’t fancy your chances of making that argument with someone in a call centre, who could be very young, or foreign, or unaware of this kind of old fashioned etiquette.
I know if I’m writing to a married couple, such as a Christmas card, I’d tend to write Mr and Mrs John Smith on the envelope, rather than using both first names.