Firstly - my condolences & sorry for your loss.
Our trade is a very tough one - with little or no empathy.
I can see why the auction house may not have any remorse for you (they probably think you’re lying - as they’ve heard that excuse serval times before).
if it’s a genuine scenario, stand your ground and show then proof (I know you’re word is good enough) but if it’s the truth stand by it - it will save you £2,400
however if you’ve bought those cars I presume to retail then & make a margin on? Why don’t you simply just buy them? Decent stock is still hard to get.