He should have queried this when he got his insurance details through, I have been in the situation before when I had a non fault claim when some mad person hit the long thin brake and not the wide thick one in her automatic car whilst in reverse.
Recently my insurance sompany got both the year and the number plate wrong on my car and I settled this over the phone straight away and they sent out another set of details.
The non fault claim should have been listed under the sections of claims and convictions in the last 5 years.
If someone has run ito the back of someone else then they should have been paying attention so the claim is a straight forward one, although at this time of the year with icey roads and low sun glare off the roads I should imagine the insurance companies are very busy and that's probably what's taking the time.