If you have just had exhaust or part of exhaust replaced, take it to where it was done and get them to do it right. Failing that, the car needs to be off the ground to get good access to the exhaust. New mountings are cheap. www.buypartsby.co.uk stock mountings at a decent price.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cars.