contact the bank or org using the cash machines
and demand the CCTV that shows you there
it is your right under the Data Protection Act
( make a data subject access request )
and dont be shocked - remember she thinks she's lost her money
all cash machines are viddied
and dont worry - we're behind you!
https://ico.org.uk/for-the-public/personal-information/
So long as you make date time and place clear
they can charge ten quid I think
but they CAN'T make you fill out a pink form of 25 pages with the words - "no formy no filmy"
post further in law if you are going down this route and the data controller starts arrissing around