I had some building materials delivered to my house from a builders merchant. They unloaded the stuff on my drive which was fine however as they drove out of my drive they crashed into my driveway wall smashing 3 blocks out. The blocks ate now broken. They stopped to have a look and advised they will pay for a builder to cement it back together. However it wont look the same. I am thinking of asking tem for £500 instead. Where do i stand with an issue like this?