My tuppence worth: When you are in an accident and it's defo the other party to blame, then you should not be at any loss. If you want to take other things in to consideration such as stress / injury etc then that's where those no win no fee type of companies come in to their own. But be under no illusion, they'll only get involved if there's a guaranteed profit in it for themselves.
You ask is the insurance industry legal robbery? It could be if you let it. I think where people go wrong is understanding how the system works. The market value of your car ( i.e. selling it ) is very different from the buying price. If you've caused the accident or rather, if it's a 'fault claim' then you receive what the car is worth, i.e. the market value. If you're not at fault, then the 3rd party should be responsible for adding the seller's profit / overheads to get you back to the position you were in before the accident. It's not YOUR insurer who does that, it's the 3rd party insurer. If you have legal cover, they 'should' be doing that on your behalf.
I never take legal cover because thru experience, I find it's their own interests in mind rather than yours, and I've ended up doing the chasing. When my car was wriiten off some years ago ( no fault claim ) and the insurer gave me the market valuation, I simply asked them to find me a car at that price. Easy peasy... no need for ombusman or anything like that, just get them to find a car for you at that price. They ended up asking me to submit several prices and I was given the average. They're claiming that back from the other party so unless it's a ludicrous figure, it's not a problem for them.
Regarding hire cars and any additional costs you incur thru no fault of your own, then if you do not have legal cover thru your own insurer, claim that direct from the 3rd party insurer.
There's no getting over the inconvenience of it all when something like this happens, but obtaining the right money for your loss and compensation is usually straight forward. You just have to be reasonable and show a willingness to be flexible about it.