Best bet is your dealer, you have not said what MMI 3G you have, DVD, HDD, SD card or HDD+
After 2011 activation is required, there are some companies and hacks around but if you mess it up then you will brick your MMI and that's not good, especially if out of warranty.
There was a recent post about someone going to a 3rd party for an update and them bricking the MMI and walking away.