i would advise the same as Jay said, let them take you to court, or pay the bill to avoid court, and then take them to court for leaving the car on an unsafe state, i'm not sure all the legal ins and outs of it all but i'm sure your solicitor would have advised this?
i know there is a site called pepipoo that i have used for motoring cases that have gone to court but not sure if they deal with anything car related as mine was just for a parking ticket and i know they do speeding tickets, there are specialist solicitors on there for these types of cases so they may know how to help you, worth a shot, and that's a free forum too