Oh my goodness....thankfully they stopped and got out for a break and were not in there when that happened. I am so sorry that happened to you. Keep bartering with the insurance company.....I had a car totalled about 3 years ago and I worked with them allot and they kept uping the money. So it does work....just keep working on them. Let us know what they find out....was the van on? Do they think someone else started this?
Again...sorry that this happened to you.