She is denying it is her fault in minor car accident, what can i do?

If your accident occurred in a busy public car park, ask the owners if they have CCTV and if so use this in your defence... if not put up an appeal notice near where the incident occurredd and ask if people remember seeing anything ( it would be nice if the pedestrian happened to see the notice) sorry if this does not help, but it's worth a try.. good luck