I think I've sussed what they have done in sending me these 2 sets of 2 plates.
They appear to have sent adaptor brackets when I asked for seat subframes.
Here's what I wanted:
https://www.demon-tweeks.co.uk/perfo...-seat-subframe
And here's what I got ( the sparco equivalent at least):
https://www.demon-tweeks.co.uk/perfo...aptor-brackets
The guy on the phone and email at Demon Tweeks has been no help, even going so far as to say he doesnt know what I'm on about as he's never done anything to a car. I've been waiting 4 weeks and I'm losing patience!