If your car was built before Oct 05 & you have SatNavPro, the mp3 software update is now available from UK dealers.
To stop them charging you for it, you need to do this:
Take it to your dealer when you're booked in for the update.
Tell them you have contacted BMW UK & the update is part of the warranty, so you DO NOT EXPECT to pay (the p*sstaking) £150 odd for it!
Let them sort it out & you should now have mp3 ability in all drives & wma in the CD changer, if you have it!
Idrive will be faster & you will be able to enter destinations into the nav by voice, if you have voice recognition!
All the best.