There are two different noises on my recently-bought 2006 Peugeot 407 SE diesel. The first is a squeaking noise occasionally from the clutch. The garage thought this was a worn ball joint and put some special grease in, but the noise remains. The second is very intermittent but alarming. This comes from underneath the car, probably the rear, and sounds as if someone is knocking loudly to come in. This noise is loud enough to alarm me even above the sound of Classic radio at high volume. I have arranged for the suspension and the fixings for the exhaust to be examined. Is this a likely problem or am I missing something important? I am going touring later next week.