If the UK withdrawal was made from a cash machine not owned by whoever has issued her card (e.g. she's with nationwide and it was a Barclays ATM) then the cash machine owners (once contacted by her building society) are allowed to take 10 working days to investigate.
I'd expect this full amount of time to pass before the refund is forthcoming but she should get all the money back. Every last penny.
As mentioned, go to the police and get a crime reference number and give this to the b-society.
Just for emphasis - as long as no-one's trying it on, she'll get the money back.