Damsel in Distress

Hi, Please could someone help me. I am in dispute with a garage :banghead: that I say damaged my exhaust system for my Rover 416 when it went in for a brake check. There was nothing wrong with the exhaust when it went on the ramps. When it came off the ramps the exhaust was blowing - basically it needed a new centre and front section, the manifold gasket had gone and was blowing and also the pipe leading into the manifold had been bent and it was blowing. The garage are saying it is not their fault but I say it is. Please could you give me your thoughts on how this could either be or not be the garages fault. Also can I ask a girlie question - is the manifold cast iron? and what about the pipes leading from the manifold to the exhaust - is this cast too or is it steel or what is it made of. I need some info so I can argue with the garage. Many Thanks Claire