This has happened to me, twice in the past 3 years.
First time, a daft bint was doing her makeup, whilst stationary at a traffic circle. She let her foot off the brake whilst looking in the mirror and bumped into the back of my car. She immediately admitted this and there was literally a hairline crack in the rear bumper, so I took it in for repairs. I had a hire car for nearly two weeks and the whole bumper had to be replaced by an Authorised Repairer, since the bump has displaced the internal bumper "dampers".
Second time, a daft bint neighbour was reversing her car and backed into my parked car outside my house. She immediately denied this and there was literally a BIG DENT in the rear bumper, and then her husband came to apologise. I took it in for repairs. I had a hire car for nearly two weeks and the whole bumper / light clusters / etc had to be replaced by an Authorised Repairer, since the bump had fooked the thing.
My insurance was not affected in either instance, since the bints were both insured through Tesco (as am I) and both claims were registered as "No Fault" claims. In fact, my insurance has dropped from £700 to £480 since then...