Like it has already been mentioned steer clear of accident management companies. They will probably charge £250 a day for the hire of the BMW when in reality the charge should only be £120.

Give your local Enterprise Rent-a-car a call- they'll be able to provide you with a premium vehicle (as long as you can justify the reason, i.e for business use etc) and if liability has been admitted you shouldn't have to pay your excess anyway. If you use this method you should also be able to choose where to take your car to be repaired, and not be dictated to.

The other option is to call up his insurance company and they should provide a vehicle for you. Usually if its someone like Norwich Union they will provide a premium product if you shout loud enough.

I don't suppose you are based in Kent?!