Well I would certainly follow the matter up if I were you.
I’d begin by contacting them by phone & just making a general enquiry as to the length of time it would normally take from the time that an application was received in their office to it being physically entered on their computer system. I would ask how long incoming post would likely be left unopened & whether it is datestamped as soon as it arrives or if this is only done when opened, or only done as they get around to entering it on their computer system.
Depending on the answer I would ask exactly when the application was received (or when they would likely have received it taking their backlog into consideration) & inform them that you were well aware of the four year statute on claims for previous years, & this is why you made sure to post your 2005 application before 31st Dec 2009.
I would point out that considering the adverse weather conditions at the time & the disruption in postal deliveries, plus the delays in their own office as well as their current backlog (both normal & as a result of industrial action) that you consider their decision to refuse your 2005 application to be extremely harsh & unfair. I would also point out that you should not be penalised for something that you did in good faith, & that it is not indicated anywhere on the revenue.ie website that applications should be sent three months in advance of year-end.
If you get no joy there I would make a formal complaint both by email & registered post (& mention in the email the fact that you have also sent a registered letter), outlining the above & requesting that in light of all of the above factors they reconsider your application & see what reply you receive. You have nothing to lose only the price of the phone call plus the €5.75 registered post fee.
Revenue TRS Helpline 1890 46 36 26
trsadmin@revenue.ie
Office of the Revenue Commissioners,
(Freepost)
Collector Generals Division,
TRS Section,
Sarsfield House,
Francis Street,
Limerick