@powers that be said:
I would have thought that it was obvious that the person responsible for the damage pays to have it fixed.
It’s not always so. Generally negligence has to be proved (tort law), but it can vary.
As per Whale’s advice, it’s often better for the damaged party to claim on their own insurance and leave any subsequent claiming of damages up to their insurance company. There is the matter of excess I know.
But if nothing else, the damaged party’s insurance company should be able to give advice on the best course to follow.