HELP! New wheelset, end cap loose on rear caused rub on chainstay.....

The description is certainly a little confusing. Pictures of frame damage? It seems like very loose cones is the most likely answer, in which case, although the wheel manufacturer may have sent it out like that, it would be down to the cyclist to stop when they notice the wheel rubbing on the frame.

so, if the wheel nuts had been tightened and everything right; the cassette/locknut shouldnt have hit the frame, ever.

but then even if the the axlenuts were not tight the cassette/locknut shouldnt have hit the frame either, as the distance between frame-cassette wouldn't be any closer. unless, the axle spacing was all wrong.

Small claims court is always worth a try although my first guess is that the bearings weren't adjusted sufficiently when fitting the wheel. Usually wheels are delivered with the bearings tightened and ready to go.

That looks to me like the bearings would have been incredibly loose. Was the wheel a bit 'wobbly' when not on the bike?

That looks like you did something similar to me (without the damage at least!), I bought some new wheels with a 142mm TA when I actually needed a 135mm.

With the 142 the axle protruded more out from the cassette as per your picture, I could just about spring the dropouts out enough to get the 142 in - but it clearly wasn't right.

When I realised I had bought the wrong thing I then ordered the 135mm version instead - which looked a lot more like your first picture; and actually fit into the frame!

If these are recent high-end Shimano hubs, the end cap is fixed on the right, threaded on the left, like a Record hub. It's impossible to unthread by hand.

How did you fit the wheels in the rear triangle given the axle was too long? Did you have to spring the drop-outs apart to get it in there?

It's a very strange issue!

Dont bite folks, it is obviously a wind-up.

If you are referring to the non-lever end of the quick-release I reckon you are up a gumtree mate.  Adjusting the QR before tightening would be your responsibility, it's part of the procedure.  

Many wheels come with a warning about correct use of the QR, I know my latest DT Swiss certainly did.  It might help your case if yours didn't?

Best of luck.

Is it the plastic covered nut that screws on to the end of the skewer (other end from the QR lever)?

end cap? nothing on the axle, including nuts, rotates so i dont think you mean this. the only thing thats near the frame that does rotate is the lock nut on the cassette, or the cassette itself, and if these were grinding the frame, then i dont think you have much of a chance of successfully claiming the wheelmaker is at fault.

have you got a pic of the "end cap"

What do you mean by end cap?

The bearing outer dust seal has worked loose?,

Im struggling to imagine this, its loose and was still rotating with the cassette, as wouldn't it be behind the cassettes locknut on the drive side?