Don't really know if this will help GC, but I have been reviewing the situation on the web. To start with, according to a legal expert in Scotland clamping on private property is illegal, but in England I'm afraid it is still perfect legal to do so!

The law is going to be changed to limit fines and clamping charges, but I have found no evidence that anything has been passed in Parliament yet.

What I have found GC amongst all the info is this company who offer (I think free initially) advise on private clamping issues:
http://www.roadsidelawyer.co.uk/questions/what-laws-are-there-regarding-a-private-parking-enforcement-company-clamping-a-car-on-private-propertyThis may not help you, but it is worth a try, as is going to the police as others have suggested on the issue of fraud over the charge for "towing" when that never took place, and the crucial point as far as I am concerned that the car was
never left unattended, a condition specified in the legal notice of this company to start clamping proceedings. They have breached their own terms and conditions, and I suspect broken at least civil law, if not criminal.
Hope you get some joy here, as I have cried over getting an 'on the road' £60 parking bay ticket, although I pursuaded the council to cancel it for legal reasons!

I can imagine how you feel about the (illegal?) £320 charge!
