The offside front spring on my 1998 9-3 cracked - it was replaced, but during this work, other original bits had to be replaced including the top suspension mount. This seems to have failed within a few weeks of being fitted. It was replaced again, but almost immediately, I'm getting the same symptoms of a knock from the front offside on turning left.
Is there something else that might be wrong that is causing the top suspension mount to fail? Can't see that two brand new mounts would have failed in quick succession.
Was the pad that sits between the spring and the strut replaced? It's soft metal that is designed to allow the spring to "bed in" but after time it corrodes and can leave a rough surface. If not replaced, it may allow the spring to move a little at the bottom.