Thanks ladies, I honestly thought I'd be hit with "that's what kids do so get over it"
If I accidentally brush up against a car when walking through a car park I freak our and check to make sure I have scratched it with my handbag.... I just assumed that everyone had the same morals as me.
The kids don't care, the parents don't care and obviously their visitors have the same careless parenting style as my neighbours because their kids were involved in today's incident and the oldest kid gave me the filthiest look when I told them to get their ball and go home.
Being an old car my husband has the tools and the ability to fix the dent but that isn't the point, an apology to my FIL would be nice but it's never going to happen