Do a search in Ireland for Cressi, a couple of places come up that might service it - Aquaholics and Waterworld. Alternatively you could look on www.divegear.ie at any Cressi regulators for sale and ask the owners where they had them serviced.
thanks for the suggestions. I looked at the divegear site, but there are no cressi regulators on it.
I'll try the other 2 companiesyou mentioned; though they are not in Dublin I could post down the regulator if they would service it.
I'll also have a look for places which sell Cressi gear and see if that turns up anything..