When I have my car serviced I rather expect the garage to shut the bonnet. If I drive off and the bonnet flips open and I crash then I would be looking to the Garage (BA) in this instance and not the manufacturer for recompense. Further, if by some good luck I didn't collide with another car or tree when the bonnet flipped open I would hardly expect my complaint to the garage to be met by a polite "no harm done mate"