Have also had poor experience with Iberia customer service. Had a small group booked returning from Spain with a connection in Madrid. Got notification a few weeks before that our flight into Madrid was cancelled and we were rebooked on to one 8 hours earlier with a long stopover in Madrid. I checked Iberia website and seats were available on flight supposedly cancelled. I rang their booking line and was told the flight was definitely cancelled.
On the day, the Iberia staff in Madrid again insisted the flight was cancelled. However it showed on the screens that it arrived on schedule, I also took screenshots of the online flight arrivals. When I made a complaint I got a standard reply apologising for the flight cancellation, saying it was out of their hands but making no reference to the evidence that the flight wasn't cancelled. A second complaint got the same reply.
As the flight originated in Spain I would have had to complain to the Spanish regulator. After a brief check online I concluded it wasn't worth it, judging by others experiences. Sounds like you may be able to complain to Irish aviation regulator, that may be more straightforward.