I've got 2 of these and I couldn't be more impressed by them, no problems whatsoever.
However well built they are and however unlikely that they'd fail I'm surprised Thule weren't a bit more accommodating.
As already said, these particular bars have an excellent reputation and I've been quite happy to recommend them to my friends.
Surely it's in Thule's best interests to sort things out on the rare occasion when they go wrong? It's not like you're trying to scam them, you're just asking for like-for-like.
I'd get back onto them myself (not via
Evans) and see where that goes. Good luck
EDIT - Just another quick thought. Are you after a replacement carrier or are you looking for compensation for your bike?
I only ask because if it's the later I'm not surprised they denied responsibility. They probably get chancers (not talking about you here) trying their luck all the time. Admitting there was anything wrong with the carrier would leave them open to all sorts of follow-up claims.
If you got in touch with them and confirmed that you were not looking for any compensation and would view a replacement carrier as the end of the issue maybe they'd be more willing to deal?