Someone drove into me on a roundabout this week and my lovely new car is no longer drivable. What made it even more stressful was that although I had the dashcam footage and a witness, the other driver claimed I drove into him. The roundabout is a very large one which has lane markers crossing it and several roads coming onto it- it's badly designed actually, but one I drive on often so I know how to use it (plus with 40 years of driving behind me I know how to use a roundabout). I had to spend a long time on the phone with the insurance company, explaining how the roundabout works - we looked at Google maps together, they had the witness statement, but it was the dashcam footage that tied it all together, and very fortunately they finally agreed that yes, he had crossed into my lane and hit me. My car will now be fixed, I don't lose my no claims bonus, and I don't have to paid my excess.
So, if you don't already have a dashcam - get one!!