I'm most unhappy - found a chunk and string of chewing gum pushed in one of my car seats today

It was a friend of a friend's "little princess" who was decided it would be funny to mash chewing gum into chairs - and she's opened our car, climbed in and mashed it in

I don't know what I'm more annoyed about - the gum or the fact the parents don't seem to be able to control the little poo. She was given a telling off by her mum, and responded with "you can't do anything to me." Sadly she seem to be right, she gets away with anything since she the "little princess".
Looking for suggestions on how to remove said chewing gum from the car seat.