unles there is an injury the police won't attend
but if there is an injury then they must attend because they need to get the particulars

so

she claims you have hit her
you have witnesses to say you didn't hit her/she rolled into you/she put it into reverse
you were stationay and had your hand brake on (because it was on a bit of a slope) and (were looking at the sign post because you were) lost and so not aware of any vehicle movements in front of you
there is a witness behind you to back up the claim that you were, in fact, stationary when the third party claims you have collided with her vehicle

with 3 independant witnesses who were there at the time and can proove they were there at the time, this would appear to be an open and shut case of her pulling a fast one

for future reference, never give out your mobile number, always give out the number of the insurance company so you have no comunication with the third party for these simple reasons that thy won't harras you wit shit like this