I bought one also in TK Maxx, Stephen's Green Centre, but unfortunately don't have a good report on it. It's an All Seasons Thermofill 4.5 + 9.5 (you can use them separately or snap together to make 13 tog), single, manufactured by Snuggledown of Norway.
We only have it about 6 months and the filling has separated inside, resulting in some parts being totally flat and others overfilled. I have sent the manufacturers an email and await their reply. They have a huge blurb on their website regarding quality, customer care etc so won't comment any more till I hear back.
At the end of the day you need to purchase a reliable brand. Normally I'm a great fan of TK Maxx (one of my favourite places for a bit of retail therapy) and in fairness it isn't their fault.
Added 13 October
Wrote to Snuggledown and received a reply that basically said sorry your contract is with T K Maxx, bring it back to them and we will refund them the price they paid us for it, possibly resulting in your receiving a refund of less than you paid for it. So much for customer service from the manufacturer - wouldn't touch them with a bargepole again.
The good news is that I took the offending duvet back to T K Maxx today and they were very attentive - gave a no hassle refund of €65. One satisfied customer! Took myself down to Dunnes and bought another for €35.