Idle musings here…
Is it possible to disable your location settings, backdate the phone and then take pictures showing the lack of parcel shelf, should this ever happen to you again? Would the exif data show no location and the time and date you set?
Persuading the shysters that you were still in their garage might be a bit more troublesome though unless you do a bit of close up or cropping.
I feel your pain. I had to deal with some horrible sales staff in Lisbon last year. I/ we cracked and coughed up for the excess insurance in the end and divvied the cost up between us.