Had my RRS HSE 2007 a week now and when i corner i hear something with a bit of weight to it slide from side to side under my seat, iv spent about an hour checking every single component and nothing is looses, iv checked up the vent outlet aswell, really running out of places to check the full interior has been takin apart and still cant find what it is, any help much appreciated!!!!!

have you checked the harmonic dampers attached to the rear end, they are weighty and are designed to swing, and have been know to hit things

Or maybe your car has the front harmonic dampers fitted and the retaining bolts have come loose? Easy to check by looking in the front wheel arch; the harmonic dampers (for which read big square lumps of iron) are bolted to the chassis just inboard of the rear lower part of the wheel arch liner. The two retaining bolts are in the big hollows in the lower face. 2008 MY Java Black TDV8 HSE

The square block has three i think bolts holding it on and its fixed on solid, i stripped the carpet back and played about with the rear passenger air vent for feet, 50% sure theres a bloody coin or somin made its way through it to the collecter under my feet , theres no way to open or remove it as its on solid peice of plastic, had the wife sit in the back and shes pretty sure the noise is coming from inside the car, sorta like metal rolling on plastic sound. So are my only options to pack the vent with rag to padden whatever is down there is there is no physical way of getting to it, should there not be guards in the vents to prevent this from happening?

I could lend you my missus She is good at retrieving loose coins (and notes for that matter) from almost anywhere
Paul

mine did just this too