general knocking (mainly from the front passenger side) particularly noticeable when going down holes or when coming off speed bumps. my top mount had actually split in two and was constantly coming apart and then almost clipping back together.
i managed to stop it for a while by soaking the top of the top mount with wd40 through the thin slits in the scuttle panel, using the provided red straw, i think that enabled it to clip fully back into itself for a while until the harsh roads over winter knocked it out again.
as mentioned above, it could also be drop links but mine are fine, no play in them, and i have mine lowered on eibach sportlines for well over a year which will be putting more pressure on them too.
but anyway, if you've only just picked it up you should be well within your rights to take it back and demand the garage (assuming you bought it from one) fix the issues, something about statuary rights for 30 days as not fit for purpose - that and usually you get some kind of warranty with a car, even a 2nd hand one.