PH wrote:Yes you might have a case, no I wouldn't pursue it.
There are lots of reasons a chain might have come off and caused the damage, some of them the responsibility of the supplier, the others not. I can't see how you'd be able to demonstrate which it was.
If it needs it, buy your own mech and hanger, maybe learn how to fit it yourself, write it off to experience and get back out cycling.
+1. I bought a bike last year on-line. It came in a box that had been factory packed by the manufacturer and still had lots to do. Great price but AFAIWC I was on my own. How would I realistically return the bike or sort things out from a distance of 300 miles? I don't even think Triton has a shop, just a warehouse. So far it's all been really fine (great purchase) but I wasn't under any illusion. I also wonder whether the OP's bike really was road-ready. If the OP gets the bike sorted (even for £100) then he's back on the road.