Bmw in Northampton want 50 quid to fit the wheel which ill pay , but say that it costs nearly 130 pounds to retrofit the cable as they have to do some sort of coding for the stereo as it dosent come with the multi function it wont work? is this true as i have a pre 09/2003 without the cable and business cd head unit, i thought it was just plug in the cable and the multi function should work , there saying there not sure so may have to charge , joke is they want me to know !! Is it just plug and play as such or do i need some sort of coding for it to work with the stereo ?