Assuming those chaps are charging say £25 a hour
I think you'll find that's Yorkshire rates
(seriously, a few years ago when I was part-based in the Glasgow area I got 3 quotes for exactly the same repair job on an X-type, and I got another 3 in the Sussex area. The Scottish prices were consistently £160-200, whilst Sussex was consistently £300-400).
Main dealer rates last time I looked were around £80-100/hour, and independents around half that - all plus VAT of course. So the rate is more likely to be about £45 + 20% = £54/hour. Plus some of the time fitting will be a 2-man job, so for that time (say 2 hours) that takes those 2 hours to over £100/hour. It soon eats into the total. Plus parts, plus shipping, plus finishing...
Not defending the quoted price as I have no idea of the parts costs, but there is also risk when doing major body surgery like this - if it all goes wrong it could lead to very major remedial costs. A prudent workshop will add a premium to help protect itself from that risk.