They can if it is being paid by his insurance and then claimed back off the company insurance. If going direct to the other insurance, the car stays as his property to do with what he wishes.

I would advise him to contact the engineer from the insurance company personally (i.e. by phone) and ask for a cash-in-lieu settlement to be agreed accordingly. The insurance would pay an agreed sum and then take no further claim or warranty. The car is not deemed a write-off then, and can be repaired as the owner sees fit.

The engineer should be happy for this as it removes all legal obligations and only means a couple of forms to be filled in, compared to shed loads for the claims dept. if it goes the other routes.

If the engineer does not agree, then get quotes showing how much one of these in identical/similar condition is worth and tell them to sort it out or you will take it further. An ombudsman will happily take a case like that on, providing you have done the above. It would then cost the insurance company £500 as soon as the ombudsman looks @ the case, even before court. No insurance company will want to go that far, so either a settlement will be given, or the car repaired.

I deal with insurance engineers all the time and I would be surprised if any of them would go past the first stage I mentioned.