I would highly recommend Revtronic for their professional and skillful business attitude.
I spoke to Pop on the phone and he clarified some issues I had with my BMW X5 DVD unit and sign posted me on how to uninstall the unit and send to Bradford as it was saying insert navigation disc.
I received a telephone call from Pop the next day advising me that my unit was in good condition and I required the professional Navigation DVD.
I paid for return postage only and my unit was returned the next day, installed and is now working well with the professional navigation disc.
Thanks Revtronic for your experience and integrity.
Daniel