If it's this one, then you've got two things that you can wave at #Halfords for the unladen weight if they try to play the exceeding the spec card.
https://parkers.co.uk/audi/a6/avant-2011/20-tdi-ultra-se-5d/specs/
Just shy of 1.7 tonne, says Parkers. Full tank of fuel will add just shy of 0.06 tonne to that, says the back of my envelope. At 1 tonne per chock, this should still be within the limit.
Interesting that it's a weld that seems to have gone. And that those other brands don't have a cross-bar there. I wonder why Halfords adds one. It does look like the failure mode that the cross-bar is aimed at mitigating is that U piece deforming outwards and the upper plate sliding down it as it does.



