Day twenty two of waiting for an answer from Irish Rail is over...linky.
I found this piece of info on the Citizens Information webpage
If you have complaints about Iarnród Éireann services, you should bring them to the attention of the relevant station manager. If you want to take your complaint further, you can contact the Customer Services (InterCity) division or the Customer Services (Suburban Rail) division of Iarnród Éireann. It is recommended that you write a letter of complaint, including as much detail as possible (date and time of travel, where you were travelling from and to and a phone number). You should also send your ticket, if you still have it. You may get an immediate response to your complaint but if not, you will get an acknowledgement within three days and you should have a full response within 15 days. You may also make complaints or raise customer services issues online . "
You will note that there is no independant place to raise a complaint about rail travel in Ireland...similar to Eircom and ComReg really in the telecoms sector.