Hi Guys, This is something I know very little about and need some help please. My S3 has built in sav nav, its deffo an audi unit but im not sure if it has been retro fitted from another car as the is a 5mm gap at the top of the unit. My issues are (bear with me I have a few): - It has a nav cd but it doesnt work and the screen says the cd is defective, do these cds expire after a certain time? - I tried playing an audio cd by putting it in the slot but it wouldn't work, is this only made to read nav cds and not audio ones? - When watching tv/ listening to a cd there is some feedback coming through the speakers like a whuuring sound, could this be an earth issue? - When I picked the car up in London I got good radio signal but now I am home in outer Surrey I can't get any signal? Could it be that the aerial is not connected properly and I only got singal in london because the signal is alot stronger up there? I never have issues with getting singals in other cars around here? I would really appreciate someones feedback on these questions as I am stumped. Thanks in advance.