Hi Bluebell,
Just to let you know I had an issue with SW a couple of years back, as they don't register PRSI stamps for the current year or the previous year unless you request it, something to this effect.
What happened was that I was trying to claim optical benefit in 2005, and they were calulating my eligibility based on the year 2003. Apparently the year 2004 wouldn't show up on their system until the end of 2005 - yes seriously. In this case, I sent them a copy of my P60 for 2004 and they accepted that the contributions had been paid on my behalf and I got the benefit I was entitled to.
This may have been what happened to your father.
HTH