Dumb woman reversed into dads car (saying shared fault)

[ILLaViTaR]

Hey guys.

Today in the carpark dad was reversing out of his park at the shops and without looking this moron starts reversing out towards dads car.
So dad stops the car and honks his horn, she doesn't hear and keeps reversing oblivious to everything she finally hits his car.

Now she admitted fault but our insurance company are saying that her insurance company will only accept shared fault, due to some stupid public liability law, they're saying it's a gray area.

Fact is this isn't a gray area, she's quite clearly at fault, it's not like they reversed into each other.

Anyone have any idea what we should do?

Cheers.