I'm afraid of that too. I think the PRTB used to take non-compliant parties directly to court - however, in the Irish Times a few weeks ago (and in a cover letter which arrived with the Determination Order), they stated that "due to the increasing volume of cases coming before the PRTB, the board may not be in a position to or may in certain circumstances deem it not cost effective to prosecute the non compliant party".
So the PRTB probably wont take them to court - in that case it will be up to the landlord to do so (Circuit Court).
Fun stuff - and as you suggest could take a lot of time.