Okay so, this will be lost on those of you who are not subject to the frustrating system that is Irish postcodes. But for those who are: aibu to think they should work flawlessly by now or just be scrapped!
I have just had my third incident of trying to place an online order and where it asked for my eircode (yay! I thought, they're looking for an "eircode" this will glide through...) so i typed in my eircode and 
no, my (correct) code is invalid. I then tried various versions : with a space, without, replaced it with random letters, switched around the correct digits, just the first three. Nope. They were all invalid. This is Debenhams Irish site, the last two times were British sites so can be forgiven for not getting our less than logical system.
So, I've had to forget about that order as I cannot order without filling in the postcode part. At this stage of the game (its been over three years) they should just work or be scrapped!