Chris,
I hope you get the problem solved.
I had a similar problem with MP brakes, it transpired it was the wrong one.
To their credit,they had a replacement sent UPS within 7 days, and I got to keep the 'wrong' one!(It was for a F*rd)
I sold it on 'Fleabay' and re-couped some of my cash!
Hopefully your supplier will 'come good' and rectify the problem soon.

Good luck
Jock thumbs_up

1950 Chevy Advance Design 3100 in Scotland
In the Stovebolt Gallery
More pix on Flickr.
I've definately got this truck thing in my blood ... my DNA sequence has torque settings
"Of all the small nations of this earth,perhaps only the ancient Greeks surpass the Scots in their contribution to mankind" Winston Churchill.